Collecting rainwater for gardening


3 ways to capture water for your backyard garden (that won’t break the bank)

One major issue a lot of backyard farmers have to contend with is water. All plants need water in order to thrive, and that generally means people have to hose down their gardens twice a day to ensure a healthy, generous harvest. With droughts and water shortages becoming more frequent, we need to be innovative when it comes to harvesting and using this precious resource: read on to find out how you can capture water around your own home, for startlingly less cost than you might have guessed.

Trashcan Barrels

For about $20, you can make a rainwater collection barrel from a simple trash can.

What you’ll need and how to make it:

A 20-gallon plastic garbage can—make sure to get one with a domed lid
Mosquito netting
A drill with a small hole saw bit
1 valve spigot that has a bulkhead fitting
Waterproof duct tape or plumbing tape
Teflon tape to secure the spigot

Step 1: Use your drill to create several drainage holes in the center of the garbage can’s lid. Then drill an overflow hole into the side of the barrel, about 3 inches down from the top.

Step 2: Cut a piece of mosquito netting large enough to cover those holes, and use the duct or plumber’s tape to secure it on the convex side. You’ll be tipping the lid upside-down to create a bowl, so you want the netting facing downwards, into the barrel.

Step 3: Drill a hole about 3 inches from the barrel’s bottom, get your bulkhead into place, and then insert the spigot. It’s a good idea to use the teflon tape around the spigot first to make sure it’s watertight, and then twist it firmly into place to secure it.

Step 4: Secure that upside-down lid onto the barrel, and seal with duct tape.

You’ll need to prop your barrel a foot or two above the ground, so stack up some cement masonry blocks or random bricks as a stand for it. Voila! It’ll catch rainwater when it falls, and the netting will prevent leaf detritus from falling into the water below.

Related: Bowl-shaped roofs harvest rainwater and promote natural cooling in arid environments

Earth Mounds

Got a shovel? Then you can make these.

Basically, this technique just involves moving soil around in your yard to create channels that direct rainwater to where you want it to collect. Pretty much every bit of land has naturally occurring microclimates: these are areas that are either higher or lower than the rest of the soil around them, or get more light (or more shade), or have different clay/sand/loam ratios. You can determine where the wetter microclimates in your own land are by doing a quick, heavy watering with your garden hose, and watching where the water runs.

You can use your shovel to dig shallow trenches to divert water to where you want it to go, and use the soil you’ve removed to build up shallow walls on either side of that trench for reinforcement. You’re essentially creating mini streams that will flow towards the plants that require the most moisture, and away from those that prefer drier feet.

Ideal areas that will benefit from this kind of diversion system are:

Trees, especially those that produce fruit or nuts, as they require a lot of water
Brassica beds: dedicated areas where you’ll grow kale, cabbage, broccoli, cauliflower, and so on
Lettuce beds: those greens are thirsty
Corn rows: its shallow roots don’t hold water well, so it needs to drink often
Legume patches: peas, snow peas, beans

Related: DIY hugelkultur – how to build raised garden beds


Say it out loud, just for fun: “mmmulch”. Satisfying little word, isn’t it? It’s also a tremendously effective way to collect (and keep) moisture in your garden. A lot of people end up watering their food gardens far more often than should be necessary because so much moisture is lost through evaporation, so the best way to combat that is with mulch.

Grass clippings, trimmed leaves from plants like squash and comfrey, and bits of bark can all be lain atop your garden’s soil—just make sure to keep it about half an inch away from vegetable stems so that it doesn’t cause root rot. Here’s a tip: lay strips of copper coil around these mulchy mounds to keep slugs away, since they won’t cross the metal barrier. Those slugs may love moist mulch, but the copper will keep them away from your vegetables.

As an aside, don’t be too overzealous with your weeding: those inedible plants may be “unsightly” as far as a traditional garden goes, but they help to keep water in the soil and prevent erosion. Additionally, if you let your chickens roam around freely, they can feed on those weeds instead of on your vegetables. Unless the unwanted plants are causing real harm, let them be.

Photos via , Unsplash and Wikimedia Creative Commons

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PHOTO: Meghan Hess/Flickrby Brien Darby March 18, 2016

For the urban farmer who wants to create a closed-loop growing system, finding a natural supply of irrigation water is important. Many people know about using rain barrels, but in some areas of the country, but there are other methods you can put to use to catch and divert rain water or—especially in the case of areas where rain catchment is illegal—maximize the use of it. Here are some water strategies you can put into place this year to have a luscious and fruitful garden.

1. Implement Rainwater Catchment and Redirection Systems

Capturing rainwater is a passive method of garden watering that can either supplement regular watering or, in some cases, take care of all the water needs for a garden. Strategies for catchment and storage of rainwater vary widely from site to site, so it can be difficult to speak in general terms about the perfect rainwater system. These differences arise from variations in roof styles, garden design, plant selection and water-storage methods. Many states in the western U.S. have strict regulations regarding water catchment and storage that often prohibit the use of rain barrels, so check with your local ordinances before designing any rainwater catchment system.

Although rain barrels have become the poster child for water catchment, it’s important to remember that they are only one piece of a larger system. The five basic parts of any catchment system are:

  • the collection area (usually a roof)
  • a water transport system (gutters and downspouts)
  • a method of trapping debris (separate, sealed catchment tube next to a downspout; a p-trap before entering the storage tank; a mesh filter between the downspout and the storage tank)
  • storage tank or barrels; in all regions, storage tanks should be enclosed
  • a system for using the rainwater in the garden (gravity fed, pump-driven, a tap for filling watering cans)

In regions where water storage is prohibited, a catchment system can still be effective simply by directing water from the roof to the garden via the position and length of the downspout.

2. Dig A Passive Rain Garden

Almost all rain gardens rely on deep digging in order to catch and hold water. To design a bed that passively catches rainwater, dig the bed in a trough shape, 1 to 2 feet deep. Fill the bed with a loose soil mixture rich in compost or humus. Humus, or finished compost, aids greatly in retaining water, whereas sandy or rocky soils tend to drain rather quickly.

Additionally, water can be directed to the rain garden with the help of downspouts, hosing attached to catchment barrels, or trenches dug into the ground. Rain gardens can also be watered by hand, but a passive system will always create less work for the gardener!

3. Strategize Your Garden’s Position

Many gardens rely on gravity to maximize the watering potential of a single rainfall. In fact, designing a garden around the existing site elevation is a key permaculture concept. When planting on a hillside or slope, position plants with the least water needs at the top of the slope and those with the greatest water needs at the bottom. The bottom bed can resemble a traditional deeply dug, trough-shaped rain garden that will collect mostly gravity-fed rainwater. However, along the slope, swales can be incorporated to temporarily trap rain and water individual gardens.

A swale is a trench, a mound or both (with the trench on the uphill side and the mound on the downhill side), built along a contour line with the purpose of detaining water on its downhill journey. Often times, tall plantings, such as fruit trees or shrubs will also be planted on the downhill side of the swale.

4. Choose The Right Crops

In most rain gardens, plants are grown in trenches that are meant to fill with water. However, this means that the plants growing in these beds must be tolerant of wet conditions, as it can take up to 48 hours for a trench to fully drain after a heavy storm. The best plants for a rain garden in any region are ones that have deep root systems and are either native or well-adapted to grow in the climate.

The following are recommendations for perennial flower, shrubs and grasses that do well in a variety of climates:

  • yarrow (Achillea millefolium)
  • false indigo (Baptisia australis)
  • northern sea oats (Chasmanthium latifolium)
  • tickseed (Coreopsis verticillata ‘Moonbeam’)
  • purple coneflower (Echinacea purpurea )
  • Maxamilian sunflower (Helianthus maximiliani )
  • bee balm (Monarda didyma )
  • ruby muhly grass (Muhlenbergia reverchonii )
  • spring and fall obedient plant (Physostegia intermedia and P. virginiana )
  • blue-eyed grass (Sisyrinchium angustifolium)

Three tree species that often perform well in raingardens are:

  • Drummond’s maple (Acer rubrum var. drummondi )
  • swamp white oak (Quercus bicolor )
  • river birch (Betual nigra )

5. Terrace Gardening

Terrace gardening is a traditional method of altering a slope in order to capture rainwater. Some of the oldest terraced gardens can still be seen in the Incan ruins at Machu Picchu in Peru. Similar to these ancient beds, contemporary terrace gardens are built by excavating a portion of the slope, using rocks or lumber to create a retaining wall, and then backfilling with an appropriate soil mixture. The challenge then and now is to build the wall in such a way that it doesn’t collapse from the weight of the soil, especially after a heavy rain.

6. Waffle Gardens

One final method of using garden design to capture rain water comes from the native cultures of the American Southwest. The Zuni of New Mexico commonly built waffle gardens for their high-value crops, such as chili peppers and tobacco. The beds are designed with 2-foot squares dug below the surface of the ground that are separated by small berms made of unamended soil. From above, this arrangement resembles a waffle. The vegetable crops are planted inside the squares where rainwater will collect and water the plants slowly over time.

by Jesse Savou

Reprinted with permission from

It might not come as a surprise that there’s no water plants love better than rainwater. Imagine your thirsty plants doused in droplets fallen fresh from the sky, their leaves expertly channeling the bounty down stalks and into the soil—right to the root zone where it is needed most.

Why is rainwater such a preferred water source? There is more than just one reason—in fact there are four:

  1. Rainwater does not contain chemicals and salts that can build up potted plants.

    Rainwater is 100% soft water. Free of the salts, minerals, treatment chemicals, and pharmaceuticals that are found in municipal water, groundwater, and surface water, rainwater is pure hydration. Salts and chemicals build up in your soil over time and these residues are tough on plants. This effect is exaggerated in potted plants where the accumulation is more pronounced. Rainwater can help flush these chemicals away and refresh the health of your soils.

  2. Rainwater is slightly acidic—naturally! Green gardeners know that most organically grown plants prefer soil pH levels between 5.5 and 6.5. This is on the acidic side of the neutral pH 7, and by nature’s design, it is the exact pH range for rainwater. City water, on the other hand, is treated to be alkaline to protect metal pipes from corroding, and can have a pH level upwards of 8.5. Greywater (once-used household water from a laundry machine, shower, or bathroom sink) will start with the same pH as your tap water, but can have a pH as high as 10.5 once it gets to the garden depending on the types of soaps and detergents that are in it. Irrigate with rainwater to flush out your soil and help keep your soil pH in perfect balance ongoing!
  3. This 6-barrel BlueBarrel Rainwater Catchment System™ irrigates a water-wise front yard with a gravity-fed drip irrigation line.

    Stored rainwater contains some organic matter. If collected from your rooftop, rainwater contains traces of organic material. While the water is very clean and should run clear, it has been exposed to anything on your roof. We’re not talking about chunks (these get pre-filtered out on their way into properly-designed rain barrels)–we’re just talking about contact exposure to leaf litter, pollen, bird droppings and the like (which perhaps not surprisingly are great for your plants). A rain barrel hosts a beneficial biology to keep the water alive – literally. It’s like a light application of fertilizer every time you water.

  4. Rain contains nitrates—an important macro-nutrient. Rainwater contains nitrate – the most bio-available form of nitrogen. Nitrogen is one of the three key macro-nutrients that plants need to thrive – necessary for the development of lush foliage. Many forms of nitrogen are not actually able to be absorbed by plants. Nitrates, which are made up of nitrogen and oxygen, are formulated by nature for maximum uptake by your plants. Plants typically absorb most of their nitrates from the soil. And where do those nitrates come from? Rain!

On a personal note, before I discovered rainwater, I doubted I would ever be able to keep a house plant alive. I had somewhat better luck outdoors in the garden, but little did I know that the potted plants were really suffering from the salt, chemical, and mineral buildup of tap water, and the high alkalinity. Then I learned about watering with rainwater. Rainwater straight from my rain barrels into a watering can is what I use for my potted plants and nursery starts. A gravity fed drip line allows me to apply rainwater directly to my in-ground garden with no effort at all. And what a difference it makes. Suddenly I have a green thumb… but (shhh, don’t tell…. rather, tell EVERYBODY!) the secret is the water.

Plant health is just one of the many benefits of harvesting rainwater. Click here for a handful of other great reasons to collect the rain that falls on your roof!

Two multi-barrel BlueBarrel Rainwatwer Catchment System™ setups maximizes rainwater storage at this home.

About the Author

Jesse Savou is founder/owner of BlueBarrel Rainwater Catchment Systems. She earned degrees in Linguistics and Spanish at Stanford before making a career shift which led her to a master’s program in Ecological Design at the Conway School in western Massachusetts. After building her first rainwater collection system as a post-grad school AmeriCorps project, Jesse launched BlueBarrel and earned her professional accreditation from American Rainwater Catchment Systems Association (ARCSA). Also a certified Permaculture Designer, graduate of the Ecosa Institute’s intensive course in Sustainable Design, and Fellow of Sonoma County’s Leadership Institute for Ecology & the Economy, Jesse understands rainwater harvesting as one of many measures to bring our households into balance with the earth’s capacity to thrive.

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How to Harvest Rainwater

There’s money falling from the skies every time it rains. Here’s how you can harvest your share. Creating a rainwater collecting and storage system is simple. (We’ll show you where to buy barrels and how to build your own.) And every time you use it to replace expensive, chemically treated city water in your garden, you’re saving money. Best of all, this collection system is right over your head. The three elements of any rainwater harvester are the collection area, the transportation system and the storage facility. Click the three areas on the illustration to the right see how to use these three elements to your garden’s advantage.

Collection area

Anywhere falling rain doesn’t soak in to the ground, the runoff can be collected. So if you have a roof, you have a collection area. Determining how much water your roof collects can involve lots of complex calculations. But all you really need to do is figure how much water your garden will need and if your roof can collect that much. The gardener who’s going to irrigate a large vegetable patch in the desert Southwest will need a lot more water than the one dousing a few container plants on a patio in the Midwest. The rule of thumb is the average 25 foot by 40 foot home roof sheds about 600 gallons of water in an hour of moderate rainfall, around 1 inch. If you have two downspouts, they’ll each divert about 300 gallons of water toward the barrel under them. The more barrels you have, the more of this water you can collect.

Transportation system

The gutters and downspouts along the edges of your roof are the water transportation system of your rainwater harvester.

Material — Gutters and downspouts can be made from aluminum or plastic. It’s the size, not the material that’s important.

Size — Gutters and downspouts have to be large enough to carry the water running off the roof. Most home gutters come 5 or 6 inches wide. 3-inch-diameter downspouts attach to the 5-inch gutters; 4-inch downspouts go on 6-inch gutters.

Forroof collection areas up to 1000 square feet, a 5-inch gutter and 3-inch downspout are large enough to carry the water. Larger roofs’ collection areas should have the larger size gutters and downspouts.

Filters — Be sure there are some kind of screens, such as the one in the illustration, to keep leaves and other debris from clogging the downspouts. In areas where mosquitos are a problem, use a fine-mesh, aluminum window screen to keep the insects away from the standing water in the barrel.

Storage Facility

Now we come to the heart of he rainwater harvesting system: Storing the rainwater you collect for use in dry times.

Barrels — There are several great water storage barrels available from specialty garden online catalogs, or you can build your own using Garden Gate‘s plan for constructing a rain barrel.

Placement — Whether you make barrels or buy them, they need to be placed properly.

Locate barrels under a downspout that’s also close to the thirstiest parts of your garden.

Dig out a 4-inch-deep area the length and width of the cinder block base. Fill the area with 1/4-inch pea gravel. This makes a base to help you level the cinder blocks and drain away water to keep your foundation dry.

The higher you can raise the barrels, the better the water pressure will be. Raising the barrels up also gets the spigot higher off the ground so you can get a watering can under it.

Capacity — Of course, you can only store the total gallons of water your rain barrels hold times the number of them you have.

Still, the system in the illustration, using three, standard 55-gallon drums, has 165 gallons of water ready and waiting to give the garden a drink when other supplies might not be available.

The more water you can store, the better. Short lengths of hose can be attached to individual barrels to link them together and boost the capacity of your system. And they can be added over time as you see how much water your garden needs.

Overflow — During heavy rains, there may be some overflow from the barrels. The 4-inch layer of gravel under the cinder blocks, as in the illustration, will divert this water away from your foundation. Or you can install an overflow port near the top of the barrel and attach a hose to divert excess water out to the garden.

Make a Rain Barrel

If you have gutters and downspouts on your house or garage, you have a fantastic system for harvesting soft, clear rainwater for the garden. The only missing piece is a collection reservoir, otherwise known as a rain barrel. To find one, check with companies that buy food ingredients in bulk. Some of their supplies come in large, seamless, plastic containers.


  • 1 clean 30- to 55-gallon barrel or garbage can
  • 1 “S”-shaped aluminum downspout elbow
  • 4 concrete blocks
  • 1 piece of aluminum window screen
  • 1 standard 1-inch hose spigot with ¾-in. pipe threads
  • 1 ¾-in. x ¾-in. coupling
  • 1 ¾-in. x ¾-in. bushing
  • 1 ¾-in. pipe thread with a 1-in. hose adapter
  • 1 ¾-in. lock nut
  • 4 metal washers
  • 1 roll Teflon thread tape
  • 1 tube silicon caulk


  • hacksaw
  • screwdriver
  • pop rivet gun with rivets
  • drill
  • pencil
  • ruler
  • spade
  • level
  • adjustable open end wrench

Scrub the inside of your container thoroughly with soap and water to remove any residues. Because they’re so hard to clean out, barrels that contained motor oil or fuel products don’t make good rain barrels. If you can’t find these barrels, you can substitute a large, plastic trash can.

Level the area for your barrel with a spade, set the concrete blocks in place and level them. To measure where the downspout elbow will come out from the side of the house and direct water into the barrel, put the barrel on the blocks. Hold the new elbow just above the top of the barrel and mark where the elbow will join the downspout — about an inch or so above the barrel is best.

Set the barrel and elbow aside and measure down 2 inches from the mark in the downspout. This will allow the downspout to fit into the elbow with a good, solid connection. Use the hacksaw to cut the downspout, then fit the elbow on and fasten it with sheet metal screws or pop rivets.

Drill a 3/4-inch hole in the wall of the barrel. Make it high enough to put a bucket underneath. Squeeze caulk around the hole on both sides. Next, refer to the illustration at right to build the spigot assembly. Connect the spigot and coupling, and wrap Teflon tape on each of the threaded ends for a tight seal. Slip on a washer and insert the threaded end of the coupling through the hole from the outside. On the inside, put a washer over the pipe and fasten everything together with the bushing.

A couple of inches down from the top of the barrel, drill another 3/4-inch hole. Then build the overflow assembly according to the illustration at right. Squeeze caulk around the hole inside and out and place a washer on the hose adapter. Push this assembly through the hole. Slip a washer and Teflon tape on the inside threads and tighten everything together with a nut. When you connect a length of garden hose to this overflow valve, you can direct some of the overflow into the garden after a heavy rain.

If your barrel has a lid, cut a hole where the new downspout elbow will direct water into it. Cover the hole with a piece of screen to keep mosquitoes out.

Finally, set the barrel back on the concrete blocks, make sure the downspout will direct water into it properly, and wait for the rain.

Rain Harvesting Sources

Commercial rain barrel and collection systems:

Food grade, 55-gallon drums:

Gardening How-to Articles

Gardening with Rainwater

By Robin Simmen | March 1, 2005

Although water may seem like a boundless resource, it is far from it. Only 2.5 percent of the planet’s water is fresh, and 74 percent of that is tied up in the polar icecaps. Groundwater accounts for another 25 percent, leaving just 1 percent of freshwater to be found in lakes, rivers, soil, and air. Due to population growth, drought, and pollution, groundwater resources are seriously declining. Today the world fights over oil; tomorrow (if not already) it will fight over water.

Gardeners can play a key role in conserving freshwater by harvesting rainwater. In addition to reducing demand on our water supplies—especially important during drought and summer (when 40 percent of all water is used outdoors)—rainwater harvesting reduces water pollution. In a rainstorm, oil, pesticides, animal waste, and fertilizers from our lawns, sidewalks, driveways, and streets are washed into sewers that often overflow into rivers and estuaries, contaminating fish and other wildlife. Rainwater harvesting prevents rain from becoming polluted stormwater and puts it to use where it falls.

The quality of rainwater is unsurpassed when it comes to watering plants and landscapes. Captured rainwater is free of the salts and pollutants associated with ground and surface water. In urban areas, the natural acidity of rainwater is good for soils that have become alkaline from cement-leached lime. The natural temperature of rainwater doesn’t shock plants with cold the way tap water can. Best of all, rainwater contains no chlorine, a chemical added to drinking water that inhibits plant growth. And rainwater is free!

Reviving an Ancient Practice

Rainwater harvesting began as early as 4,000 years ago in the Middle East, where runoff was collected in ditches for crop irrigation. Ancient Romans collected rainwater in underground cisterns and interior pools, where it slowly evaporated and cooled their homes. Up until a few generations ago, municipal water didn’t really exist in America, and many folks relied on captured rainwater to meet their needs. Even today, large areas of the world, including the entire continent of Australia, still depend primarily on rainwater for their water supply.

Jeff Anderson and Eric Zobrist designed these upside-down umbrellas to harvest rainwater for irrigation and to shade the Papago Buttes Corporate Plaza in Tempe, Arizona. (Photo © Heather Kinkade-Lavario)

Community gardeners have been among the first to revive rainwater harvesting in the U.S. In New York City, for example, since the drought of 2002, the Water Resources Group (WRG), a collaboration of community gardening and environmental organizations, has helped build demonstration rainwater harvesting systems in more than 20 community gardens. These systems together divert around 250,000 gallons of rainwater from NYC sewers each year.

Many cities have adopted creative, low-cost ways to stop wasting rainwater. Seattle Public Utilities has sponsored wildly successful sales of residential rain barrels, and Austin offers rebates of up to $500 for installation of rainwater harvesting systems. In Canada, Toronto offers a free service to homeowners to disconnect downspouts from the sewer system and install rain barrels, available at a discount.

Designing a Rainwater Harvesting System

Regardless of how much rain your area gets or how big your landscape is, you can design a rainwater harvesting system that works for you. The most common method of capturing rainwater for irrigation involves taking rain from building gutters and storing it in an outdoor tank or rain barrel.

Lenny Librizzi, assistant director at the Council on the Environment of NYC and a founding member of the Water Resources Group, says, “It isn’t easy to come up with ‘one size fits all’ instructions for building rainwater harvesting systems because of variations in styles of roofs, downspouts, storage tanks, and garden layouts. You have to use a combination of research, common sense, ingenuity, and dumb luck to design and build your system.”

Ideally, rainwater harvesting systems for irrigation include five basic components:

  • Catchment or collection area—usually a roof;
  • Transport for the water, such as gutters, downspouts, and piping;
  • Roof washer to intercept the first flush of rain (plus any debris or bird feces) from the roof—usually a sealed downspout next to the main downspout;
  • Storage tank or barrels;
  • Gravity- or pump-driven system for distributing water to the garden.

Bear in mind that only nonpotable usage of rainwater is described here; harvesting rainwater for drinking involves several levels of filtration as well as chemicals for disinfection.

The first step in designing a rooftop system is to analyze (and, if you need to, change) the roof-surface materials. Roof material affects both the amount of water collected and its quality. For example: Porous asphalt shingles and rolled roofing are less desirable than smooth steel (although all are used successfully) because rough materials absorb more water and bird feces. Roofs made of wooden shingles treated with chromated copper arsenate are not appropriate for rainwater harvesting. Zinc antimoss strips mounted on roofs also produce toxic chemicals that you want to keep out of your garden.

Most people already have gutters and downspouts attached to their roofs to transport rainwater away from the building. Ideally, the gutters should be covered with a leaf screen to keep debris from entering the system. If you want to be able to divert water from your downspout during the growing season but shunt it back down the drain off-season, you can install a downspout diverter. These simple devices usually cost less than $20 at local hardware suppliers or on the Internet (for product information in this article, see “Rainwater Harvesting Resources”).

Numerous roof washers and diverters are available, ranging in price from around $50 to over $600. For example, the Smart-Valve, from Flo True International, can be adjusted to flush away the first 10 to 60 gallons of rainwater and accommodates roofs up to 2,500 square feet. However, many small-system rainwater harvesters forgo separate roof washers and depend solely on the screens built into their barrel lids to filter out debris.

Rain barrels can be hooked together with pipe to increase storage capacity. Note how these recycled barrels have been elevated on cinder blocks for better water pressure. (Photo © Lars Chellberg)

You can store rainwater in barrels, tanks, underground cisterns, or anything that protects it from contamination. Barrels made from dark materials block sunlight and discourage the growth of algae. A good rain barrel or tank has a tight-fitting cover to prevent evaporation and mosquito breeding. Water is heavy—a 500-gallon plastic tank filled with water can weigh more than two tons—so be sure your storage unit has a proper foundation and good support.

Rain barrels range in size from 40 to 80 gallons and, fitted with spigots and screened lids, sell from $60 to $200 a piece, but you can construct your own unit using recycled plastic barrels. These are widely available, especially from companies that ship food products. Instructions for outfitting your own rain barrels are available on the Internet and from the Water Resources Group. Rain barrels can be linked with hoses or pipes to gather water from one downspout, thus expanding storage capability. Be aware, however, that every hole and pipe fitting in your system represents an opportunity for leakage, probably the biggest problem you will face.

To figure out how much water you can collect from your roof, calculate your roof size and the average rainfall for your growing season. A good rule of thumb is that one inch of rainfall on a 1,000-square-foot roof produces 600 gallons of water. Maybe this is more than you bargained for in terms of storage, so be sure to install an overflow pipe near the lid of your system to carry away excess water.

To store a lot of water, you may want to invest in a polyethylene tank that can hold up to several thousand gallons. Be prepared to spend about one dollar per gallon of storage capacity. Polyethylene bladders are another alternative. Bladders can be ordered in many shapes and sizes for insertion into hard frames. Although bladders are relatively cheap compared with barrels and tanks, they don’t last as long. Look for polyethylene bladders that are UV stabilized and 20 to 30 millimeters thick.

Directing the Flow

You’ll also need to move water to the landscape. Most simple systems are gravity fed, meaning the rain barrel or storage tank is elevated above the area being watered. Many gardeners build small platforms from concrete blocks for their rain barrels and secure the barrels against building walls. More elaborate foundations with concrete footings are required to stabilize larger tanks. Consider connecting a passive drip irrigation system to your rainwater supply via the main spigot or the overflow pipe. Hand pumps can be used to draw stored rainwater up from underground tanks or to move it uphill across landscapes. Solar-powered pumps are another renewable-energy option. At the very least, plan to fit a watering can under a spigot at the bottom of your tank or barrel.

In 1998, Ole Ersson received approval from the city of Portland, Oregon, to use rainwater collected in this tank.

Don’t forget to design where the overflow will go! Every rainwater system has its storage limits and should be fitted with an overflow outlet. Planting a rain garden to absorb the overflow is one of the most creative ways of using it. Or the overflow could be used to fill a dry streambed and send water to a thirsty grove of trees. You don’t have to waste a single drop.

Although rainwater harvesting systems are low-tech, they do require minimal yearly maintenance. In the spring, clean any winter debris from your gutters and roof. Inspect and clean tank lids and barrel tops, paying special attention to their vents. Fill the system with a few inches of water to check connections for leaks. In the fall, before the weather freezes, remove drain plugs from the bottoms of barrels and open the main spigot to drain all barrels and tanks so that trapped water doesn’t freeze, expand, and damage the system.

Rainwater Harvesting Resources

Further information

The NYC Water Resources Group offers a map of community gardens using rainwater harvesting systems, as well as how-to videos and a guide to designing your own system from recycled barrels. A book on rainwater harvesting, Forgotten Rain, by Phoenix-based landscape designer Heather Kinkade-Levario, can be purchased online at

Rain Barrels and Cisterns

Rain barrels are widely available. One good source is Clean Air Gardening. A tool kit for outfitting your own recycled barrel can be purchased from the Garden Watersaver. Large, polyethylene tanks and cisterns are available from Snyder Industries. Tanks are also available from Arid Solutions Inc.

Diverters and Roof Washers

Flo True International sells the Smart-Valve roof-washing diverter. The Water Filtration Company manufactures a filtering roof washer. Downspout diverters can be purchased from the Gardener’s Supply Company.

Robin Simmen is a former director Brooklyn Botanic Garden’s community greening programs. She has an MA from the Conway School of Landscape Design, a BA from Cornell, and a lifelong interest in gardening.

The trees in our three-year old mini-orchard are thriving thanks in part to plenty of watering

When we first began to clear the land for our little farm in the fall of 2010 – one of our biggest concerns was water – or should I say, lack of water at the property.

Without a well or natural spring – we worried about how we would supply water to our future fruit trees, mini-vineyard and landscape plants – not to mention the hundreds of vegetable plants we planned on growing in the garden!

But as we head into the 2015 growing season nearly 5 years later, we have yet to dig a single well – and yet – those initial H20 worries are nothing more than a distant memory!

We use reclaimed rain water to water our entire garden

How so? Well (no pun intended), with the addition of few simple and inexpensive rain water collection systems set up around the farm – we now have more than enough water stored on site for all of our needs and more.

The best part of all, these methods can be easily adapted to almost any home to handle your outdoor watering needs as well, saving valuable natural resources from your well or city water supply – not to mention saving you the money it takes to use them!

It’s also a huge benefit to your plants considering that rain water won’t contain any of the trace chemicals that many find in their tap water.

Use and Adapt Existing Gutters…

Using the basic 32′ gutters from the barn – we can collect almost 250 gallons of rain water during a single rain

One of the easiest ways to begin collecting water is from existing gutters and downspouts. With the simple and inexpensive installation of a water diverter to your existing downspout, and the addition of a holding tank for storage – you can collect and store hundreds of gallons of rain water every time Mother Nature sends it down from the sky.

That is exactly what we did when we built our barn that very first year, and it quickly allowed us to collect and store the much-needed water for our newly planted trees and garden. (see: Building our Recycled Barn)

The barn itself is a standard rectangular structure measuring 32′ long x 26′ wide.

Through a simple in-line diverter – the rainwater is carried to our main capture tank

It has a standard gabled metal roof measuring 13′ wide x 32′ long on each side – with a 32′ section of guttering runs along the bottom of each side of the metal roof that to carries the rain water down to the side of the barn – much like that of any standard house or outbuilding.

From there, both sides empty into standard downspouts – and it’s there at those common downspouts where our water-collecting magic starts.

Creating a simple rain water collection system

About 5′ off of the ground, we installed a simple 2-way in-line diverter to the downspout (see picture to the right). When the metal lever is slid to the left, the rain water is diverted from the normal downspout into a 275 gallon storage tank that we located on the side of our barn. And with every rain, the tank fills with precious water. So much in fact, that in a single two-hour downpour – we can collect as much as 125 gallons or more!

When the tank is full, the switch can be slid back for normal drainage.

Don’t Forget Outbuildings…

If for some reason your house or barn are unable to work as your collection source – don’t forget about using those small outbuildings you might have on your property.

We use our home-made corn crib to store extra leaves we collect each fall.

The very same process can be used on small structures such as sheds, chicken coops, garages and more – and don’t think for a minute that because the buildings are small, that they won’t collect a large amount of rainwater.

We installed an 8′ section of gutter on the back of our tiny corn crib – and fed the downspout into an additional tank up by the garden. From that tiny 8′ x 3′ wide roof – we collected a full 275 gallons of water over the course of a few hard spring rains – and it allowed us to water our entire garden all summer.

What to Collect The Water In..

As for what to collect your water in – although there are commercial (and expensive) rain storage tanks and barrels on the market – you can utilize recycled plastic 55 gallon drums or large plastic totes to keep it on the cheap. We found our totes for $40 each after a quick search on Craigslist – and with each of them holding up to 275 gallons of water – we can store several weeks worth of watering in a full tote.

Recycled water totes are a great way to store and use rainwater – just make sure your totes are clean and were not used to hold harsh chemicals that could leave harmful residues.

In addition to Craigslist or local selling walls, you can also check with local food plants that may receive their raw materials in them.

One word of caution – no matter what you use, make sure you know what was originally in your tanks or barrels and that it is safe. Our tanks were used to hold maple syrup and molasses – simple food products that can be cleaned out and re-used. You will want to avoid using tanks that held harsh chemicals, or are of unknown origin. Most tanks come with a 6″ threaded cap on top, and a 2″ threaded outlet valve at the bottom. You can convert the bottom 2″ valve to accept a standard garden hose with a few adapters found at your local hardware store.

Keep It Dark and Keep It Covered:

You will want to keep the water from getting direct sunlight to keep algae from growing in the stagnant water. Algae can only grow if there is light. If your tank is translucent like ours, you will want to cover it. We use a black tarp to cover them up once the sun and algae become a problem. Not only does it dress it up, but it keeps the water and the flow line crystal clear.

You will also want to keep your storage tanks closed. Water that sits is an open invitation to mosquito larvae . Our totes came with 6″ caps and lids on the top. We simply cut out the hole for the downspout, and then sealed the edge with some inexpensive foam.

Know What To Use The Water For:

We use our stored water for landscape and maintenance needs – not for drinking

Be safe with what you use your water for. We use our reclaimed water for watering trees, landscape and garden plants – and for washing off equipment, etc. Since we do not treat it in any way, we do not use it for drinking.

Last – check to make sure your allowed to collect rain water in your state. Although it sounds crazy (and is!), in some states out west you are not allowed to collect rain water, as the water rights still belong to the state. So to be on the safe side, check with your local or state government to make sure it’s legal where you live.

Happy Water Collecting! Jim and Mary

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How To Easily Collect Rain Water For Your Outdoor Watering Needs Tagged on: collecting rainwater garden watering how to collect rain water rain water harvest water water collecting watering your garden

The 9 Best Ways to Collect Rainwater

According to the UN, water is considered a precious commodity and integral resource. It’s only natural to want to discover different methods of more efficient collection methods, to ensure availability and save money at the same time. Capturing rainwater is also a smart and cost-effective solution for helping the environment. Redirecting rainwater helps to ensure it doesn’t become polluted runoff.

If you want to find more sustainable and cost-effective ways of collecting and conserving water, employing a variety of creative but efficient methods of collecting rainwater is one of the best strategies to preserve this vital resource.

There are countless ways to conserve rainwater; here a just a few of the most effective ones!

1. Rain Water Barrels

Building rain barrels to collect rainwater is an effective method of not only saving money but, also, conserving water, as well as contributing to a more sustainable homestead.Conserve run-off rainwater in 55-gallon rain barrels.They can be wooden or plastic.

You can find them at your local hardware or home improvement store. If you have the materials and are handy enough around the house,you can even build a rainwater barrel yourself.

The trick is to position the tanks’downspouts where the rainwater is funneled and runs off the roof. You can even use the conserved rainwater for your garden by connecting your garden hose to the tank’s valve.

You will find that new rain barrels available at home improvement stores are now equipped to prohibit pesky mosquitoes, animals, and even small children from accessing or tampering with the barrels.

2. Rainwater Collection Systems

In the same vein, rainwater collection systems, also known as rainwater catchment systems, are typically comprised of large underground tanks used for collecting rainwater from the roofs or gutters of homes. From there, the system filters the water, and the purified result (gray water) can be distributed throughout the entire household.

You can use your rainwater collection systems for a variety of tasks around the house that require water, like general garden upkeep, watering the lawn, washing the car, or even showering.

The potential downside to installing these systems in your home is that the system costs can add up if you are not careful, depending on what you want to use the gray water for. The more uses you want the rainwater for, the more likely you will need professional installation. For certain types of systems, you may need a pump/pressure tank to distribute and move the water to its desired location. You may even be able to make the water potable by adding a filtration system.

3. Rainwater Chains

Decorative and functional, rainwater chains are an attractive way to collect rainwater. Normally made from copper or other metals, rainwater chains work as water collection devices through cups that run the length of the chain. Rain chains can be used instead of downspouts and are easy to install. All you need do is remove the downspout and place the hook through the pipe, and then fasten with a tension hook. By placing a collection device such as a decorative barrel, you can collect the rainwater.

4. Rainwater Tarp

The rainwater tarp method is one of the simplest methods you can use to collect rainwater. All you need is a tarp, PVC pipe, and a container or barrel. Essentially, you must detect and use changes in elevation to make the process work. This elevation shift can take the shape of a slope or a small hill. The slope or hill will determine the direction the water will flow through.

Next, you need to create mounds at the edges of the tarp for the water to be collected. This step can be accomplished by shaping the dirt underneath the tarp into a square-shaped mound. You will also need to secure the tarp, which can be accomplished by evenly placing weights, such as rocks, throughout.

Placing the PVC pipe at the corner of the lowest part of the slope toward the collection center will be the next and final step.

It’s that simple!

5. Rainwater Gardens

Rainwater gardens are another effective option that can be used to conserve rainwater. Rainwater gardens typically use run-off rainwater from roofs, gutters, driveways, etc. to not only grow vegetation and flowers but,also,to effectively filter out 90% of chemicals (like pollutants, fertilizers, harmful chemical compounds, garbage, and bacteria, to name just a few) commonly found in runoff.

These types of gardens are also useful and commonly used to curb and prevent flooding as well. Besides having a beautiful-looking garden that’s healthy and watered, you can also enjoy the benefits of minimizing pollution, conserving water, improving overall water quality and reduce the number of mosquitoes during the summer time.

6. Plastic-Lined Pond

Similarly, a plastic-lined pond is another simple way to collect rainwater. First, you must construct a pond. A good size is 26 feet long by 16 feet wide and at least 5 feet deep, as these dimensions can accommodate most liners. Make sure the hole has elevated edges for better water collection. Then place a plastic pond liner—which cost around $150 at your local hardware store—over the square shaped hole.The pond is connected via gutters and pipes to an elevated structure such as a house.

7. Install a Cistern to Help Water Your Garden

A 1,000-square-foot roof can capture about 600 gallons of water. Use this water to irrigate your vegetable garden or water your flower beds and lawn. Simply direct the water from the downspout to a cistern. A cistern has been a common storage unit for rainwater collection for centuries, and they are used all over the world. They are typically covered and can be above ground, partially buried, or underground. The tanks can be constructed from a variety of materials such as metal, plastic, and fiberglass.

8. Green Roof

If you don’t want to worry about barrels, ponds, or other more labor-intensive capture methods, once you prepare your roof this system is the easiest to maintain and use.

Cover your rooftop with a liner and plant garden beds with plants that require little gardening other than water. You will need gutters or some system to get rid of the runoff.

This method has the additional benefit of adding another layer of insulation to your house.

If you want, you can combine this method with one of the others by capturing the runoff in barrels or by one of the other methods listed here.

9. Unconventional Methods

Although not the most conventional of methods, finding household products or inventing/using unique objects to conserve rainwater is always a great idea. Inflatable swimming pools, watering cans, even large pots are all effective in collecting rainwater to use for plants, the lawn, washing the car, or other miscellaneous purposes. Be sure to monitor large items like children’s swimming pools, however, as mosquitoes use stagnant water for breeding.

Check Your State Laws

Every state has different laws regarding rainwater harvesting. Check your local state laws before you begin rainwater conservation.

Support water conservation. Share this post with your friends and family.

Here’s some beautiful flowers as a thank you.

Images Sources:

A Better Rainwater-Harvesting System

Your Improved Rainwater-Harvesting System

To store as much rainfall as possible in your garden soil, you can set up a rainwater irrigation system that diverts your roof runoff water directly onto your garden beds (or lawn, if you prefer).

This rainwater-harvesting system relies on gravity to carry rainwater from your downspouts out into your garden or lawn. For it to work, the area you choose to irrigate must be level with or below your downspout. If your garden is not near a downspout, you may need to modify your setup, perhaps attaching a larger pipe to the downspout to carry the water out to a manifold and a set of perforated hoses in the garden.

Step 1: Go Shopping. Study the illustrations in the Image Gallery, and then head to a hardware store and buy one or more standard plastic trash cans. Get rectangular ones if you can — they will fit up against the wall behind your downspout a little better than round ones. (If you already have a rain barrel, you can just use it.) In the lawn and garden department, look for a hose manifold that will let you attach several hoses to it (see illustration in the Image Gallery). Next, you’ll need one manifold per trash can. Go to the plumbing department and find a clerk who can locate the bulkhead fitting you’ll need in order to attach the hose manifolds to your trash cans. Printing this article and taking it along to show the clerk what you’re planning to do may be helpful.

Step 2: Install the Bulkhead Fitting and Manifold. Cut a hole near the bottom of the trash can, attach the bulkhead fitting to the can, and then screw on the manifold.

Step 3: Cut a Hole in the Trash Can Lid; Install the Can Under a Downspout Near Your Garden. If there will be leaves in the water coming off the roof, you may want to cut the downspout off above the trash can and install a screen over the entrance hole into the trash can. The screen will allow water from the downspout to enter but will prevent leaves from being washed into the can and clogging the manifold.

A small screen secured over the bulkhead entrance in the bottom of the can is also a good idea to keep debris from clogging the hoses. To prevent mosquitoes from breeding between rainstorms, drill a few small holes in the bottom of the can so water can drain away completely after each storm.

Step 4: Install Perforated Hoses. Decide which areas you want to direct the rainwater to, then round up some old garden hoses. If you don’t have any, ask around — many of us can seldom bring ourselves to throw out hoses even after they’ve aged and begun to leak. Cut them to the lengths you need, and then cap the ends or fold the ends back and secure with wire. Drill holes in the hoses every foot or so, and then attach them to the manifold. You could also buy no-pressure soaker hoses designed to work with gravity flow from Mr. Drip. (Commercial low-pressure soaker hoses will not work well with this setup.) If you use irrigation ditches between your crop rows, you can skip drilling holes in the hoses and just lay the hose ends in the ditches.

Each time it rains, roof water will flow into the trash can and out through the manifold to wherever you’ve directed the hoses. Check the system during a heavy downpour to confirm that the hoses are distributing the water where you want it. You may need to add more holes or possibly tape some holes closed.


Rainfall patterns vary greatly from region to region, but even if most of your rain comes in fall or winter, this system will let you store it right in your garden beds. (Be sure the manifold is fully drained during cold weather to prevent damage from freezing.) If you have periods during which your garden gets too much rain and the soil reaches field capacity, you can simply redirect your hoses away from the garden for as long as you need to.

There’s a bonus to using this DIY rainwater-harvesting system: If the rain doesn’t come often enough and you need to irrigate using your household water supply, you can just aim your main hose into the trash can and turn on the water, and your network of hoses will distribute the water wherever you want it.

Cheryl Long is the editor in chief of MOTHER EARTH NEWS magazine, and a leading advocate for more sustainable lifestyles. She leads a team of editors which produces high quality content that has resulted in MOTHER EARTH NEWS being rated as one North America’s favorite magazines. Long lives on an 8-acre homestead near Topeka, Kan., powered in part by solar panels, where she manages a large organic garden and a small flock of heritage chickens. Prior to taking the helm at MOTHER EARTH NEWS, she was an editor at Organic Gardening magazine for 10 years. Connect with her on Google+.

Using Rain Barrels: Learn About Collecting Rainwater For Gardening

How do you collect rainwater and what are the benefits? Whether you have in interest in water conservation or simply want to save a few dollars on your water bill, collecting rainwater for gardening may be the answer for you. Harvesting rainwater with rain barrels conserves potable water — that’s the water that’s safe to drink.

Collecting Rainwater for Gardening

During the summer, much of our potable water is used outdoors. We fill our pools, wash our cars and water our lawns and gardens. This water must be chemically treated to make it safe for drinking. which is great for you, but not necessarily great for your plants. Collecting rainwater for gardening can eliminate many of these chemical salts and harmful minerals from your soil.

Rainwater is naturally soft. The less water used from your local treatment facility, the fewer chemicals they have to use and the less money they have to spend on those chemicals. There’s savings for you, too. Most home gardeners see a rise in their water bill during the summer gardening months and during a drought, many of us have been forced to choose between our garden and out water bill.

Rainwater collection can reduce your bills during the rainy months and help offset your costs during the dry ones. So how do you collect rainwater? The simplest method for harvesting rainwater is with rain barrels.

Using rain barrels involves no special plumbing. They can be purchased, often through local conservation groups or from catalogs or garden centers, or you can make your own. Prices range from around $70 to $300 or more, depending on the design and aesthetics. The price drops considerably if you make your own. Plastic barrels can be painted to blend with your house or landscape.

Using Rain Barrels

How do you collect rainwater for use in the garden? On the most basic level, there are five components. First of all, you need a catchment surface, something the water runs off. For the home gardener, that’s your roof. During a 1-inch rainfall, 90 square feet of roof will shed enough water to fill a 55-gallon drum.

Next, you’ll need a way to direct the flow for rainwater collection. That’s your gutters and downspouts, the same downspouts that direct the water out to your yard or storm sewers.

Now you’ll need a basket filter with a fine screen to keep debris and bugs from your rain barrel, the next component of your rainwater collection system. This barrel should be wide and have a removable lid so it can be cleaned. A 55-gallon drum is perfect.

So now that you’re using rain barrels, how do you get the water to your garden? That’s the last component for collecting rainwater for your garden. You’ll need a spigot installed low on the barrel. An additional spigot can be added higher on the drum for filling watering cans.

Ideally, when using rain barrels, there should also be a method for directing overflow. This can be a hose connected to a second barrel or a piece of drainpipe that leads to the original ground pipe to lead the water away.

Harvesting rainwater with rain barrels is an old idea that has been revived. Our grandmothers dipped their water from the barrels at the side of their house to water their vegetable patch. For them, collecting rainwater for gardening was a necessity. For us, it’s a way to conserve both water and energy and to save a few dollars while we do it.

Note: It is important that you safeguard rain barrels by keeping them covered whenever feasible, especially if you have small children or even pets.

How Rain Barrels Work

­Rainwater is relatively pure stuff. The process of evaporation leaves chemicals behind, and what you see falling from the clouds starts out pretty clean. It picks up particulates, pollution, pollen and dust as it makes its way to the ground, but even those contaminants become less of an issue if it’s been raining for a while and the air is cleaned with a good water scrubbing.

Evaporation is nature’s distillation process, and the fresh water you’re drinking out of the faucet was a raindrop at some time — maybe a number of times — in its long history on the planet. It’s true that tap water has been treated with chlorine and other chemicals to make it safe to drink, but for nondrinking uses, rainwater is a good, wholesom­e choice.


Besides being natural, rainwater is usually soft, which makes it a good option for watering your flowers and plants. Actually, the absence of those very chemicals that make tap water safe for drinking makes rainwater a better choice for your outdoor watering needs.

Supplementing your water needs with rainwater will reduce your utility bills, at least during the summer months. It will also reduce the drain on groundwater resources. As communities grow, the demand for water can outstrip the supply. Municipal water districts often rely on groundwater or aquifers that can become overtaxed. Supplementing our collective water needs with a little rainwater can help postpone the costly expansion of water treatment facilities groaning under the weight of population growth, an aging infrastructure and urban sprawl.

In some areas, using rainwater may mean the difference between keeping your lawn and plants alive or watching them die of thirst. In times of drought, when there are restrictions on water use, rainwater may be the only available source of water for landscaping and washing the family car. It may come down to a choice between rainwater and no water at all.

Reducing the demand for water helps protect the local ecology, too. Water that isn’t being diverted into municipal water systems stays in the lakes and river­s to sustain fish, birds and other wildlife. Besides relaxing some of the demand on existing water resources, harvesting rainwater reduces the amount of polluted rainwater runoff. Dirty rainwater is often released from storm drains directly into lakes and streams, causing big problems for plants and animals. Imagine the chemical stew you see on the roadways, like oil and antifreeze, washing directly into your favorite brook or creek.

In the next section, we’ll take a closer look at how much water you can expect to harvest from your down spouts.

Why rain is better than tap water for houseplants


Question: I catch water in buckets out on my deck to collect and water my houseplants. Ever since I started doing this, my houseplants have thrived. Can you shed some light on why rainwater is better than tap water for plants?

Answer: Rainwater tends to be way more pure than tap water, city or well. Rain contains few salts, minerals, treatment chemicals or pharmaceuticals often found in municipal tap water.

Though relatively pure, rainwater can contain particulates from the atmosphere, such as dust or pollen. Those of us who grew up in the Cold War era were told not to eat snow or drink rain, as they carried radioactive fallout from above-ground nuclear testing.

Well water can be very hard because it contains minerals from the bedrock it comes from. My well water is really hard and sulfury. It leaves a white residue on my dishes and on my houseplant soil. My water leaves rust stains on my toilet.

When you water with tap water, whether it be well water or municipal water, salts and chemicals may build up in your houseplant soil. Do not water your plants with softened water, as it contains an excess of sodium as far as plants go. Excessive salt in the soil prevents the roots from absorbing water. Over time, this may affect your houseplant soil and roots.

Most plants tolerate unsoftened tap water. But fluoridated municipal water may cause build up of fluoride in soil, which might eventually stress houseplants, especially those with long, slender leaves, such as the spider plant. It helps to leave chlorinated and/or fluoridated water out overnight at room temperature in an open pitcher to let the fluoride and chlorine gas evaporate before watering plants.

Municipal water is commonly treated to be slightly alkaline to protect metal pipes from corroding or leaching. This is not optimal for acid-loving plants such as African violets or orchids.

Collected rain is usually naturally slightly acidic, so it can help flush away the build up of accumulated substances from alkali tap water deposits in your potting soil.

I just set a bucket out in my yard to collect rainwater, fresh from the sky. Fresh bucket-collected rainwater is tops in purity for plant watering. It is easy to collect, at least during the rainy season.

If you collect rainwater from your gutter downspout or a rain barrel, via your roof, the water may contain traces of contaminants from your roof, especially if you have composite shingles, as well as contaminants from bird droppings and other creatures like squirrels who may spend time on your roof. These may be OK for plants, but don’t drink this water.

Stored rainwater may contain some organic matter, in the form of insect larvae or algae growth. Rain also contains traces of nitrates, essential for plant growth.

If you filter or distill your tap water, then it is better than straight tap water for your houseplant. Reverse-osmosis filtered tap water, deionized water or distilled water doesn’t contain the chemicals that unfiltered water contains.

To learn more about municipal water sources and quality in the Salem region, visit the League of Women Voters of Marion and Polk Counties informative web page on local water systems:

No matter what kind of water you use to water your houseplants, make sure it is at room temperature to avoid stressing the root systems of your plants. Make sure your pots have drain holes as saturated soil or standing water may damage or kill root systems. And don’t forget that overwatering kills more houseplants than under-watering. For most plants, you can wait until the top inch of soil feels dry to the touch before watering. Houseplant soil should not be soggy, just slightly moist.

The difference between rainwater, tap water, and groundwater

There really isn’t a competition between water sources for your beloved cannabis plants. Most domestic water available to the average indoor grower should be trouble-free.

It is second nature to check pH, and the use of chlorine varies all over the world. Just ask your local infrastructure authority for their water assessment. It is an easily obtainable document that will have a broken down analysis of your water.

A simple rule of thumb is that if you wouldn’t drink the water yourself, don’t use it to mix nutrients for your plants.

A confronting reality is that human pollution has penetrated deeply into the ecology. To talk of rain as a pristine water source has been a fairytale for decades.

The poisonous trace of human consumerism has insinuated itself into mountain springs and aquifers. Molecular plastic, novel chemistries not seen in nature, and raw pollution are difficult to avoid anywhere at all.


Ostensibly, all water is rainwater—being a general term to cover water in all its forms coming from the sky. A majority of the world’s major rivers and aquifers swell with water as rain comes down and snow melts.

Many go on to fill dams that feed cities with water and hydroelectric power. Except for glacial water sources and prehistoric water trapped in rock strata, all water was rain at some stage.

Rainwater does have some magical properties, but they are short-lived. Once it is contained, the momentary benefits of extra molecules fizzle away as the water reaches equilibrium. Every gardener has noticed that plants react with great vigor after being drenched by rain.

Much more so than after a simple watering from above. These peculiar qualities of rainwater are fleeting; once captured in dams and cisterns, barrels or tanks, it becomes mere fresh water.

Rainwater is usually mildly acidic, with dissolved carbon dioxide making very weak carbonic acid. After rain, the alchemy of plants absorbs the carbon dioxide out of the rainwater acid solution, and the plants get a growth spurt. Similarly, nitrogen can be dissolved in rain water, giving plants a second boost of an essential molecule.

A generous rain seeps deep into the ground, wetting the complete root systems of the plants, carrying its payload of extra nitrogen. Saturating rain penetrates much more efficiently than artificial watering. Most people will not water their outdoor plants enough.


Groundwater is generally okay. Potable water is always sought for humans, plants, and livestock. Wells or aquifers that have unbalanced pH because of dissolved solids, such as calcium from limestone, are tolerated as a necessary evil when there are no better sources of water available.

It is advisable to get an assay of your water if it is particularly hard. If your soap doesn’t lather and the water is not thirst-quenching, there are minerals present making the water more alkaline.

TDS meters only measure total dissolved solids, they cannot tell you which particular solids are dissolved. It is usually calcium and sodium chloride, but if you really want to know, water assays are available. If it’s a private well or bore, you are going to have to pay for an analysis.

Wells and aquifers have played an integral part in the evolution of many human civilizations not near the coast or navigable water. When far from rivers and tributaries, wells and groundwater are of great importance.

There are countless towns and cities in the mountains of the world where the town centre is a water source. The Ancient Silk Road was strung between water sources.


Tap water for the urban grower could be from a number of sources. Anything listed above are all used for tap water. The majority of urban water supplies are filtered before reaching the consumer.

Ultraviolet sterilization and reverse osmosis are often used on industrial scales to clean billions of litres of water for human consumption. Always a topic that can raise controversy.

Fluoride and chlorine are added to many domestic water supplies. It is a personal choice. These chemicals do not really exist in nature in a form that can be absorbed by living things. Yet they do perform a primary public sanitation service. In-home, domestic-scale water purifying units are common and inexpensive if you want to be sure.

Older cities may find their water hardening as minerals build up in old infrastructure. Similar things happen with older houses that may get scale deposits building up in old pipes, which can harden water.

Simple devices are available for the contemporary grower that can give you information that will warn you of such water troubles. An EC/pH/TDS meter is one of the fundamental tools in the grower’s arsenal. Use it often. It is your friend.


Toxin-free, well-oxygenated, clear, pH-balanced water is one of the cornerstones of a good cannabis grow. Water is quite safe in most of the developed world. Quality may fluctuate from source to source, but the swing in quality usually stays within a human-friendly range.

If it is okay for you to drink, it will usually be okay for your plants.In fact, you are a much more sturdy organism than a plant. If your plants get ill, it is an early warning system for you to check the water you are consuming yourself.

Here are some basic guidelines to keep in mind. You want your water to be in pH range 5,8-6,2 depending on the plant life stage to remain in full safety zone. If your native water has below 150ppm TDS (Total dissolved solids), you can use it without further filtering.

If your water has above 250ppm at the start line, consider doing an analysis to break down the ingredients before you mix in fertilizers.

As much as short term you might not see a point of that, in longer perspective it will help you fine tune your feeding schedules and nutrition plans to meet exact needs of your plants.

Rain Barrels Part IV: Testing and Applying Harvested Water to Irrigate a Vegetable Garden

Summer months are the time of year when having a rain barrel can really be useful. Heavy thunderstorms fill up rain barrels quickly, storing water for hot, dry days when there is no rain in sight. Rain barrel water is usually soft, meaning free of dissolved minerals and slightly acidic which is excellent for nutrient uptake by plants.

One of the most common questions asked about rain barrels is whether water harvested from a rooftop is safe to use on a vegetable/herb garden. Limited studies have been conducted focusing on the safety of roof runoff for vegetable garden irrigation. Gardeners often collect water in a rain barrel with little to no protection from the roof ‘s “first flush” of runoff. The first flush water is the initial rainwater that drains off an impervious surface, such as a driveway, parking lot, or roof and has been shown to have the highest levels of contaminants. Larger rain water collection systems (cisterns) that collect hundreds or thousands of gallons of water are normally installed with a first flush diverter which reroutes the first few gallons of rainwater away from the storage container. Rain barrels are often not installed with this feature.

Research has shown that roof runoff can have high levels of pathogens, zinc (Zn), lead (Pb), and polycyclic aromatic hydrocarbons (PAHs) (Bannerman et al., 1993; Clark et al., 2008; DeBusk, 2009; Van Metre and Mahler, 2003; Gikas et al., 2012). These metals and compounds may be hazardous to human health if ingested in specific concentrations. The question is whether these levels are high enough to be of concern for a backyard or community gardener who uses a rain barrel to water a garden grown for consumption.

This fact sheet summarizes the findings of one New Jersey study investigating the water quality of rain barrel water (Haberland, Bakacs & Yergeau, 2013). In addition, recommendations are made for testing rain barrel water and how to safely utilize rain barrel water to irrigate a home, community, or school garden.

Water Quality Study

Twelve rain barrels were installed during the summer of 2011 on homes that have asphalt shingled roofs, the dominant roof surface on New Jersey houses. Six barrels were located in a suburban community and six in an urban community to help determine the effect of surrounding land use on rain barrel water quality. Samples were collected six times from each barrel over a four month period from July-October. Water samples were collected 3–7 days after a rain event in order to mimic the amount of time a homeowner or community gardener would wait before using the collected runoff. Samples were analyzed for PAHs, Pb, Zn, and total coliform and Escherichia coli (E. coli) bacteria. E. coli is a species of bacteria that is specific to fecal matter from warm-blooded animals such as squirrels and birds. The presence of E. coli indicates the potential presence of human pathogens (i.e., bacteria), and is important information if rain barrel water is used to water a vegetable garden.

Having a standard against which to compare the level of contaminants in the roof runoff is important for determining the safety of the water for irrigation. Table 1 shows the water quality standards against which the data were compared. Both Pb and Zn were compared to the United States Environmental Protection Agency (USEPA) reclaimed water (treated waste water) guidelines (USEPA, 2012) for agriculture irrigation because no other irrigation standards exist for these parameters. No irrigation standards exist for total coliform. E. coli results were compared to the US Food and Drug Administration’s (USFDA) proposed standards for “Growing, Harvesting, Packing and Holding of Produce for Human Consumption” (USFDA, 2011).

Results were also compared to the New Jersey Drinking Water Standards although in New Jersey harvested rainwater can not normally be used as a source of drinking water per the Safe Drinking Water Act (NJDEP, 2011).

Table 1: Water quality standards for comparing test results

Parameter Federal Irrigation Standards NJDEP Drinking Water Standards1
Lead 5.0 mg/L2 0.015 mg/L
Zinc 2.0 mg/L2 5.0 mg/L
Total coliform (counts/100 mL) n/a based on presence/absence
E. coli (counts/100 mL) geometric mean= 126/100 mL3
single sample limit= 235/100 mL3
based on presence/absence

1USEPA, 2012
2USFDA, 2011. The standard calls for maximum E. coli levels in agriculture irrigation water of <126 counts/100 ml for the geometric mean (must have 5 samples) and <235 counts/100ml for one sample.
3NJDEP, 2011. Coliform bacteria standards are based on the presence or absence of coliforms in a sample. When collecting less then 40/samples per month, no more than one coliform sample can be positive.

mg= milligrams, L= liters, mL= milliliters


Results of this study showed that overall the water quality of the rain barrel water was very good. Heavy metals were well below federal irrigation standards for reclaimed water and posed minimal risk for irrigating a vegetable garden. PAHs were not detected in any samples. Results also showed the majority of water samples to be below recommended irrigation guidelines for E. coli. Table 2 shows the percent of samples that violated the federal irrigation standard and the New Jersey drinking water standards.

1USEPA, 2012
2USFDA, 2011
3NJDEP, 2011

  • Zn values did not violate any of the water quality standards although Zn levels were higher in samples taken from urban barrels than the suburban barrels. Atmospheric Zn can come from tire dust and industrial processes (Councell, 2004). Both increased traffic and industrial processes involving metals may be the reason Zn was higher in urban samples.
  • Pb values did not violate the irrigation standards at any site. Three of the samples violated the drinking water standard for Pb. The main source of Pb is most likely from atmospheric deposition due to industrial processes, manufacturing industries, waste incineration, and airborne soil dust (USEPA, 2006a). Pb results showed no difference between urban and suburban land uses.
  • Total coliform violated the drinking water quality standards at all sites for all samples. This is not necessarily a concern for irrigating vegetable gardens though because total coliform is found in rainwater and is a poor indicator of human pathogens.
  • E. coli violated the irrigation standards in 9% of the samples collected. E. coli violated state drinking water standards in 66% of the samples collected. In this study, potential sources of pathogens were wildlife (i.e., birds, squirrels) that had access to the roofs that were monitored or living in trees adjacent to the homes.

Best Practices and Recommendations

Even though a low percentage of samples exceeded the irrigation limits, caution is still warranted when using harvested water to water a vegetable/herb garden to reduce the risk of exposure to a harmful contaminant like E. coli. Below is a list of recommendations for pathogen treatment and best practices for utilizing collected rain water to irrigate vegetable/herb gardens.

  • Rain barrel users should make sure to clean the barrel with a 3% bleach solution before collecting water to irrigate a vegetable/herb garden. Household, unscented bleach with a 5–6% chlorine solution can be added at the rate of 1/8 teaspoon (8 drops) of bleach per gallon of water. A typical 55 gallon rain barrel would need approximately one ounce of bleach added on a monthly basis. During periods of frequent rainfall, bimonthly treatment may be necessary. Wait approximately 24 hours after the addition of bleach to allow the chlorine to dissipate before using the water. Note that household bleach is not labeled for use in water treatment by the Food and Drug Administration although it is frequently recommended for emergency disinfection of drinking water (USEPA, 2006b).
  • When using harvested water to irrigate a vegetable garden, care should be taken to avoid getting water on the plant itself. Harvested rainwater should only be applied to the soil, possibly through drip irrigation. A watering can may be used, as long as the water does not get directly on the plant.
  • Water should be applied in the morning only. Produce harvesting should not take place right after watering in order to benefit from leaf drying and ultraviolet light disinfection.

Testing Harvested Rainwater

Guidelines on using harvested water often recommend having the water tested by a commercial lab to determine the safety of using the water on an edible garden. The results of this study show that testing harvested water at the necessary frequency needed to draw meaningful conclusions about the water quality is impractical and too expensive for the average homeowner, community, or school garden. Rather, it is recommended that the rain barrel user automatically treat the water, and take appropriate best practices, if it will be used to irrigate a vegetable/herb garden.

However, testing may be necessary to comply with state or federal guidelines. For example, school or community gardens may have to test water sources used for irrigation to show that the produce is safe for student consumption. The National Food Service Management Institute recommends testing non-municipal water sources for a school garden annually (NFSMI, 2011). The following steps should be followed for having the water tested.

  • At a minimum, E. coli testing should be conducted. Local county health departments may perform this type of service for residents or may have a list of water quality laboratories that test for E. coli. The NJDEP lists water quality labs on their website by county at In addition, it may be possible to have the water tested through a local well water testing program. It should be made clear to the laboratory that the water is utilized for irrigation purposes and not for drinking water.
  • Most laboratories provide sampling bottles. The water sample should be taken from the rain barrel’s faucet or hose and not dipped into the top of the barrel.
  • Pathogen samples must be kept in a cooler in ice and returned to the laboratory within six hours of taking the sample.
  • Results can be compared to the irrigation standards for E. coli listed in Table 1. For individual samples, if E. coli values are under 235 counts/100ml then the water would be safe to use for irrigation.


Based on study results, rain barrel water can be safely utilized to irrigate a vegetable/herb garden. Pathogen treatment should be conducted and best practices utilized when applying the water. Testing rain barrel water is not a practical method for the average homeowner or community/school garden for determining water quality but may be necessary based on state guidelines. Additional information on water quality considerations for harvested rain water can be found in Mangiafico and Obropta (2011).

December 2013

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A variety of pollutants can get into rain-barrel water, which is why it’s generally recommended to be used only on ornamental plants, not edibles.

(George Weigel)

Q: I have been using a rain barrel for several years and added a second one this spring. I read a magazine article recently that stated that this water should only be used on ornamental plants… never on vegetable plants. Is that true? Or is rain-barrel water OK for edible crops?

A: From the research I’ve read, I’d lean toward caution and stick with the magazine advice: use your rain-barrel water for flowers, trees and shrubs, not edibles.

Rutgers University, the Washington State Department of Ecology and others have measured rain-barrel water for pollutants, and the bottom line is that this water is probably safe for edibles in most cases.

While that’s fine if you have the right kind of roof, know the exceptions, and take the right precautions, it’s also possible that this water is polluted beyond safe drinking water standards.

The basic problem is that metals, chemicals and possibly petroleum or plastics byproducts can leach off of the roof and out of your gutters along with the rain water.

A second problem is that roofs can have varying amounts of bird poop, squirrel excrement and other potential bacterial contaminants.

When Rutgers and Washington researchers measured various pollutants, though, most came in under levels that met acceptable safe-water standards.

However, runoff from wood-shake roofs, for example, were significantly more polluted than runoff from asphalt roofs. Copper roofs, as you might guess, produced elevated levels of copper in the collected water.

Water from a “first flush” following a long dry spell also tended to be more polluted than water following frequent rains.

Then there’s the variable of which crop you’re planning to water and eat. One study, for example, found that beans and beet leaves had significantly more lead in them than kale leaves that were watered with the same saved water.

Yet another variable is whether you’re eating parts that came into contact with water-polluted soil or polluted water itself as opposed to, say, a fruit growing well above the ground.

That all gets too complicated for most people, which is why most publications go with the blanket conclusion that it’s better just to avoid rain-barrel water on edibles altogether.

If you’re determined to try it anyway, first read the Rutgers and Washington research to see how your type of roof material fared in the studies.

To get around possible bacterial contaminants from bird and rodent droppings, disinfect your water with an ounce of bleach per 55 gallons of water for 24 hours before using.

Then don’t water veggies over the leaves (directly into the ground only), and wash and peel any crops before you eat them.

The Sightline Institute, a Pacific Northwest environmental group, has an excellent rundown on this whole issue if you want to read more. It leans toward using rain-barrel water for edibles… with precautions.

I’m wondering if it is safe to use water from a rain barrel on my vegetable garden?

With winter seemingly over, we all hope, and spring on the way, that’s a timely question. Spring in Chicago is generally rainy and we can all benefit from the use of rain barrels. Rain barrels collect rain water and cut down on our use of water from our hoses for our non-potable water usage. I personally know gardeners who are perfectly comfortable using the water from their rain barrels on their vegetable gardens. They assume that if we wash our vegetables and fruits before we eat them, using water from a rain barrel is no different then using water from a hose. Personally, I think this makes sense. Even if we are using treated water from a hose on our garden, our pets, neighbors pets, and the usual assorted wildlife, as well as the chemicals from our yards and our neighbors yards could be contaminating our produce. Washing produce properly before eating it should take care of any contaminants from any source.

However, if for any reason, you are uncomfortable with using the water from a rain barrel directly on your vegetables or fruits, that water can be used at the roots of the plants from a drip hose or a watering can instead. Apply water from your rain barrel to the soil around your plants rather than on the plants themselves. This allows the soil to perform its role as a filter and, if you amend your soil with plenty of compost, helps to trap compounds that you might be concerned will be taken up by your plants.

Even if you choose not to use water from a rain barrel on your edible gardens, there are still lots of places in your yard that you can use the water from a rain barrel with no concerns at all. Use a rain barrel, at the very least, to water your ornamental plants and lawns. Using a rain barrel saves money on your water bill and also helps by reducing the energy used to purify the water before it is used in your yard. Using a rain barrel can benefit your pocketbook and the environment.

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