- Determine the location of your rain barrel, preferably right under a downspout. Then, place it on a flat, raised surface. You can use cement blocks or bricks.
- Remove the rain barrel from the raiser and place it sideways on the ground. Drill a hole towards the bottom, on the side of the barrel. This is where you’ll remove water from the rain barrel. The hole should be a bit smaller than your spigot hole.
- Add both metal and rubber washers to your spigot.
- Apply waterproof sealant around the rubber washer. Place inside the hole and hold in place for 20 seconds.
- Reach inside the barrel and add a rubber and metal washer onto the other end of the spigot. Some homeowners add a hose clamp if they experience heavy storms. This ensures the spigot will hold in place.
- Cut an entry hole on top of the barrel. This is where your downspout or diverter will go. The hole should be just big enough for the diverter to fit. You can use a hacksaw or utility knife to cut.
- Drill two exit holes, on the sides of the barrel, towards the top. In case your rain barrel is filled, these holes will release some of the water and unnecessary pressure.
- Cut enough landscaping fabric to fit over the rain barrel. This fabric will prevent mosquitos, leaves, and other debris from entering the rain barrel.
- Open the lid and place the cut fabric over the open rain barrel. Close the lid. The fabric should be sticking out of all ends just a bit.
- Cut your downspout so it can be placed inside the rain barrel.
- If you’re adding a diverter, measure the diverter and saw off your downspout as needed.
- Attach the diverter as instructed.
- Place the connecting tube to the port and place in the rain barrel.
- Test the system by pouring water into your gutter from a ladder. Always have someone hold the ladder. If water is not entering the rain barrel, there is likely a blockage or hole in the gutter or downspout.
- Harvesting Rainwater: How to Make a Rain Barrel
- Obtaining a Rain Barrel
- How to Make a Rain Barrel
- How to Install a Rain Barrel
- How To: Make a Rain Barrel
- 1. Rubberneck Rain Barrel
- 2. Blue HDPE 55 Gallon Barrel
- 3. Wine Barrel Rain Barrel
- 4. Rain Barrel from 330 Gallon Drum
- More Homemade Rain Barrel Resources and Guides.
- Eco-Friendly DIY Rain Barrel Ideas
- 1. Garbage Can
- 2. Toilet Flushing Rain Water
- 3. Wine Barrel
- 4. Stand Alone Rain Collector
- 5. Rustic Rain Barrel
- 6. Pickle Barrel
- 7. Elevated Dual Barrels
- 8. Plastic Bottle Rainwater Pipe
- 9. Bottom Filled Rain Barrel
- 10. Condensation Reclamation
- 11. Solar Powered Water Barrel
- 12. Underground Rainwater Storage
- 13. Recycled Pallet Stand
- 14. Rainwater Disguise
- 15. Galvanized Stock Tank
- 16. Stacking Barrels
- 17. Wood Decorated
- 18. Stylish Rain Barrel
- 19. Medium Sized Rain Water
- 20. Painted Rain Barrel
- 21. Drip Line Irrigation
- 22. Pretty DIY Rain Barrel
- 23. Oldschool Rainwater Filter
- 24. River Rocks DIY Rain Barrel
- 25. Sticker Barrel
- 26. Gutterless Rain Barrels
- 27. Beautiful Rain Barrel
- 28. Blue Whisky Barrel
- 29. Rainwater Planter
- 30. Duo Gravity-Fed Rain Barrels
- Now you have a Great Selection of DIY Rain Barrel Ideas
- Was this article helpful?
- How can we improve it?
- We appreciate your helpul feedback!
- Veggies irrigated in stormwater
- A closer look at roof runoff
- Bird droppings and bacteria
- Hedging your rain barrel bets
- Related posts:
Harvesting Rainwater: How to Make a Rain Barrel
Obtaining a Rain Barrel
Practically any large waterproof container can be used to make a rain barrel. One easily obtained candidate is a trash can, preferably plastic, with a snap-on lid. A standard 32-gallon can will work for a rain barrel, but if you can find a 44-gallon can choose it instead. Although wood barrels are becoming more scarce, you can still get them from wineries. A used 55-gallon barrel can be obtained free or for a small charge from a bulk food supplier. Most 55-gallon barrels today are plastic, but some metal barrels are still floating around. Whatever the material, make sure the barrel did not contain any chemical or compound that could be harmful to plants, animals, or humans. If you don’t know what was in it, don’t use it. Choose a barrel made out of opaque material that lets as little light through as possible, reducing the risk of algae growth.
A barrelful of water is an appealing breeding ground for mosquitoes and a perfect incubator for algae. Filters and screens over the barrel opening should prevent insect infestation, but for added protection against mosquitoes add one tablespoon of vegetable oil to the water in the barrel. This coats the top surface of the stored water and deprives the larvae of oxygen.
How to Make a Rain Barrel
Tools and Materials
- Barrel or trash can
- Drill with spade bit
- Hole saw
- Barb fitting with nut for overflow hose
- 1 1/2″ sump drain hose for overflow
- 3⁄4″ hose bibb or sillcock
- 3⁄4″ male pipe coupling
- 3⁄4″ bushing or bulkhead connector
- Channel-type pliers
- Fiberglass window screening
- Cargo strap with ratchet
- Teflon tape
- Silicone caulk
- Cut a large opening in the barrel top or lid. Mark the size and shape of your opening — if using a bulk food barrel, mark a large semi-circle in the top of the barrel. If using a plastic garbage can with a lid, mark a 12-inch diameter circle in the center of the lid. Drill a starter hole, and then cut out the shape with a jigsaw (see Image Gallery).
- Install the overflow hose. Drill a hole near the top of the barrel for the overflow fitting. Thread the barb fitting into the hole and secure it to the barrel on the inside with the retainer nut and rubber washer (if provided). Slide the overflow hose into the barbed end of the barb elbow until the end of the hose seats against the elbow flange (see Image Gallery).
- Drill the access hole for the spigot (either a hose bibb or sillcock, brass or PVC). Tighten the stem of the sillcock onto a threaded coupling inserted into the access hole. Inside the barrel, a rubber washer is slipped onto the coupling end and then a threaded bushing is tightened over the coupling to create a seal. Apply a strip of Teflon tape to all threaded parts before making each connection. Caulk around the spigot with clear silicone caulk.
- Screen over the opening in the top of the barrel. Lay a piece of fiberglass insect mesh over the top of the trash can and secure it around the rim with a cargo strap or bungee cord that can be drawn drum-tight. Snap the trash can lid over the top. Once you have installed the rain barrel, periodically remove and clean the mesh.
How to Install a Rain Barrel
Whether you purchase a rain barrel or make your own from scratch or a kit, how well it meets your needs will depend on where you put it and how it is set up (see Image Gallery). Some rain barrels are temporary holding tanks that store water runoff just long enough to direct it into your yard through a hose and drip irrigation head. Other rain barrels are more of a reservoir that supplies water on-demand by filling up watering cans or buckets. If you plan to use the spigot as the primary means for dispensing water, you’ll want to position the rain barrel well off the ground for easy access (raising your rain barrel has no effect on water pressure).
In addition to height, other issues surrounding the placement of your rain barrel (or rain barrels) include the need to provide a good base, orientation of the spigot and overflow, the position relative to your downspouts, and how to link more than one rain barrel together. Tip: Wherever possible, locate your rain barrel in a shaded area. Sunlight encourages algae growth, especially in barrels that are partially translucent.
Tools and Materials
- Hack saw
- Rain barrel
- Hose & fittings
- Base material (pavers)
- Downspout adapter and extension
- Teflon tape
- Select a location for the barrel under a downspout. Locate your barrel as close to the area you want to irrigate as possible. Make sure the barrel has a stable, level base.
- Install the spigot. Some kits may include a second spigot for filling watering cans. Use Teflon tape at all threaded fittings to ensure a tight seal. Connect the overflow tube, and make sure it is pointed away from the foundation.
- Cut the downspout to length with a hacksaw. Reconnect the elbow fitting to the downspout using sheet-metal screws. Attach the cover to the top of the rain barrel. Some systems include a cover with porous wire mesh, to which the downspout delivers water. Others include a cover with a sealed connection (next step).
- Link the downspout elbow to the rain barrel with a length of flexible downspout extension attached to the elbow and the barrel cover.
- Connect a drip irrigation tube or garden hose to the spigot. A Y-fitting will let you feed the drip irrigation system through a garden hose when the rain barrel is empty.
- If you want, increase water storage by connecting two or more rain barrels together with a linking kit, available from many kit suppliers.
Variation: If your barrel comes with a downspout adapter, cut away a segment of downspout and insert the adapter so it diverts water into the barrel.
Reprinted with permission from DIY Projects for the Self-Sufficient Homeowner, published by Creative Publishing International, 2011.
How To: Make a Rain Barrel
Rainwater collection has an ancient history with archeological evidence dating back at least 4,000 years. Urban demand created the centralized water systems we use today, but that doesn’t mean harvesting water doesn’t have benefits to home gardeners.
Collection is easy and a necessity in drought-prone regions. In fact, many cities throughout the country offer incentives like tax rebates to encourage citizens to install rain barrels. And if nothing else, the pleasure of a lower water bill might be a motivation to take a few minutes for the installation of a rain barrel.
There are lots of variations in the supplies you can use in your garden, but the basic necessities include:
MATERIALS AND TOOLS Available on Amazon
• A gutter and downspout to channel rainfall runoff from the roof—you could use either a PVC-type rainfall diverter that prevents overflow or a plastic flex hose.
• A storage tank or cistern—this could be as simple as a trashcan, fiberglass cistern, or steel drum. Get one that is opaque in order to discourage algae growth.
• Something to stop debris from ending up in the tank—this can simply be a screen at the top of the gutter or a strainer basket at the mouth of the cistern.
• Cinder blocks
• A hose spigot and soaker hose with pressure-reducing washer removed
Find the gutter where you will be collecting and unscrew the downspout. Cut a notch into it with tin snips, so that the diverter fits snugly within. Reattach the diverter and downspout to the house wall, then lead the diverter’s plastic hose to the rain barrel.
Alternatively, do away with the downspout entirely by attaching a plastic flex hose to the gutter and leading the water to the rain barrel. (By doing it this way however, you’ll have to remove overflow from the rain barrel manually.)
Place the rain barrel on level concrete cinderblocks to raise the barrel above ground level (and to let gravity assist in watering your landscape). Install screens to prevent leaves and twigs from accumulating and contaminating the water.
After drilling a hole and screwing in the spigot and attaching the soaker hose, you’re all set. Please keep in mind that this water is for the garden, not for drinking!
For more on rain barrels, visit our slideshow: Rain Barrels That Perform with Style
Want more How To? Browse all projects in 30 Days of Easy Summer DIY
© Ramon Gonzalez
Rainwater harvesting relieves our aging sewer systems from the stress of heavy storms while lessening the impact of our garden on our water bills. Whether your interest in rain barrels is because of frugality, or they are environmental, making your own rain barrel is easy.
Here are four examples and instructions for making your own rain barrel.
1. Rubberneck Rain Barrel
Instructables user, Donnie Dillon, hacked a trashcan he had in the garage into a rain barrel after a trip to the hardware store that only cost him $38.22 for the materials. The project took less than 2 hours and after he was done, he could harvest rain water to water his plants and chickens, wash his car and fill up his squirt guns. For walkthrough instructions see his Rubberneck Rain Barrel Instructable.
2. Blue HDPE 55 Gallon Barrel
This blue barrel is the most common item converted into a rain barrel. Instructables user, stylnpzzalvr, spent some time creating barrels like these and selling them at farmers markets for $50. His directions for a homemade rain barrel show you how to create one for $15.00, and offers tips on how to find barrels on the cheap.
3. Wine Barrel Rain Barrel
Chouf/CC BY-SA 2.0
While functional, blue plastic is not very attractive, and if your rain barrels face the street (or annoying neighbors) something that looks more natural may suit your needs. Wine and whiskey barrels can also be converted into rainfall catchment systems. Chouf, at Instructables, went with the wooden rain barrel for his because he did not want the blue to interfere with the aesthetics of his future deck.
4. Rain Barrel from 330 Gallon Drum
If a 55 gallon drum is too small for your needs, perhaps these 330 gallon drums will be more to your liking. Over the past two years, I have been seeing them used in homes and urban agriculture projects. In the comments of his video Coastguard1010 explains how he fitted the spout of this drum to fit his water hose.
More Homemade Rain Barrel Resources and Guides.
The Whatcom County Extension has PDF guides for asimple rain barreland analternative rain barrelthat you can load onto your e-reader if you want to have instructions in your hand while building yours. TheTexas Manual on Rainwater Harvesting(PDF) is an extensive reference on rainwater collecting, but may be useful if you are the kind of person that needs more than a cursory understanding of harvesting rain. Use mosquito dunks to kill mosquitoes to prevent creating a breeding ground for mosquitoes.
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Does your water bill scare you? This may especially occur when Spring comes around and you’re trying to get all your little plants into the garden, they need lots of water to blossom, and therefore you end up paying.
Water is an invaluable resource that we tend to take advantage of. It falls from the sky and we let it run off our properties without thinking twice about it! But why wouldn’t we collect that water and use it for ourselves?
Only a hundred or so years ago this was the “norm”. Most people had rain barrels on their properties and used them to water their gardens, do their laundry, or even sometimes (if they had a good enough filter) drink! With time passing and society changing this knowledge seemed to get left behind. Though once again, more and more people are concerning themselves with their ecological footprint.
So, whether you want to lessen your monthly water bill, become more eco-friendly, or just take on a new project to add to your yard, creating your own DIY rain barrel water collecting system is a wonderful idea! Below are 30 different DIY rain barrel tutorials to help you get started!
Eco-Friendly DIY Rain Barrel Ideas
1. Garbage Can
Making your own rain barrel can be as simple as updating a forgotten garbage can. This tutorial will walk you through all the steps you need from filtering to pouring.
2. Toilet Flushing Rain Water
Collecting rainwater can be useful for many reasons. Some use it to water their plants, others use it as the water needed to flush the toilet. Learn how to set up this DIY rain barrel system here.
3. Wine Barrel
An old wine or whiskey barrel makes a very efficient rainwater storage system. More importantly, however, is that it’s aesthetically nice!
4. Stand Alone Rain Collector
This design is so cool! It’s not only an efficient way to collect and store rainwater, it also doubles as an umbrella and patio table! Enjoy a beer with your fellow gardeners as you simultaneously collect rainwater!
5. Rustic Rain Barrel
Rainwater collecting systems don’t have to be an eyesore, there are plenty of ways to create beautiful structures that are useful and lovely to look at. This one is complete with a rock bed to prevent mud when overflow occurs.
6. Pickle Barrel
Here’s an example of how you can recycle an old food barrel! This one in particular held pickles. What’s good about using barrels such as these is that you can be sure they are food-grade.
7. Elevated Dual Barrels
Search your local online marketplace to find affordable and clean barrels that you can turn into a rainwater collecting system. Placing the barrels at a height allows for easy gravity-fed options.
8. Plastic Bottle Rainwater Pipe
People never cease to amaze me with their cleverness and ingenuity! Reuse those plastic bottles to not only capture and direct water but to filter it as well.
9. Bottom Filled Rain Barrel
This particular rainwater barrel design was created with overflow in mind. The design is made so that there is little to no overflow. To understand better see the tutorial here.
10. Condensation Reclamation
This design has been created to collect the condensation from an indoor air conditioning unit. Let’s collect as much water as possible on our properties!
11. Solar Powered Water Barrel
This design involves that you equip a solar panel. Why? Because that solar panel is going to charge the pump of your system so you can water your plants with pressure!
12. Underground Rainwater Storage
Bury an old IBC tank underground add a simple pumping system and voila, you’ve got yourself a great and functional rainwater system!
13. Recycled Pallet Stand
If you are wanting to get that gravity-fed goodness, you can build your water tanks a special stand out of recycled pallets!
14. Rainwater Disguise
Disguise your ugly rainwater barrel with this absolutely brilliant idea! Keep your backyard looking lush, green, and fresh!
15. Galvanized Stock Tank
For a cool and rustic look why not transform an old galvanized stock tank to become your new rainwater collection system.
16. Stacking Barrels
Stacking rainwater barrels is a great way to maximize space as well as water retention. I also like the idea of painting the barrels to match the color of your walls.
17. Wood Decorated
Having a rainwater barrel doesn’t have to be an ugly addition to your yard. With a little creativity, you can help it become a beautiful and unique piece.
18. Stylish Rain Barrel
No need to hide your rainwater barrel when it’s already stylish enough to leave out for everyone to see. Love the color of this one.
19. Medium Sized Rain Water
If you live in an area that fluctuates between extreme wet and dry seasons, having a larger rainwater barrel could be a smart idea.
20. Painted Rain Barrel
Make your rain barrel fun and unique by painting it with your own unique design, or copy this one! It could be fun to do a project with the kids!
21. Drip Line Irrigation
Attaching a drip line irrigation system directly to your rain barrel is an awesome and super efficient idea. It not only keeps your plants happy by watering them slowly but it makes you happy by doing the work for you!
22. Pretty DIY Rain Barrel
A simple barrel rainwater system that has been disguised with paint and decorated with beautiful stones and plants.
23. Oldschool Rainwater Filter
Collecting rainwater was extremely common only a hundred or so years ago. For gardening, it’s best to leave the rainwater unfiltered, but for household use, you can create a simple and cheap filter.
24. River Rocks DIY Rain Barrel
A similar yet different way to filter your rainwater is with a bed of river rocks. It not only cleanses the water it looks pretty too!
25. Sticker Barrel
If you are looking for a way to make your rain barrel just a little more visually appealing, a simple and cheap way to do so is by using wall stickers.
26. Gutterless Rain Barrels
Even if you don’t have a gutter on your house, that’s no excuse for not collecting rainwater! Here is a clever idea of what I mean.
27. Beautiful Rain Barrel
This rain barrel is perfect! It’s beautiful to look at, efficient, and functional! I love that they have planted flowers on the lid to make it look even more lovely.
28. Blue Whisky Barrel
Out of sight, out of mind. Here is a DIY tutorial on reusing a discarded whiskey barrel to have a purpose once more. The purpose is not only saving a valuable resource but your water bill too!
29. Rainwater Planter
This project skips the barrels altogether and goes straight from the gutter to plants! Reusing old pallets, this planter looks beautiful filled with colorful flowers.
30. Duo Gravity-Fed Rain Barrels
Stacking barrels allows gravity to take over and eliminates your need for a pump. Collect as much water as possible with more and more barrels!
Now you have a Great Selection of DIY Rain Barrel Ideas
So as you can see there are lots of ideas out there on how to create your very own rain barrel water collecting system. There are barrel ideas that blend in with their surroundings, others that stick out in a pleasant fashion, and those that are there just to get the job done. Choose the one that best suits your needs and desires and give it a try! However, if DIY is not your thing, see our review of the best barrels to purchase.
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Editor’s note September 2017: Fall is here! It’s the perfect time to build a rain barrel to capture your roof’s rainwater and keep your plants happy in the summer. A two-fer!
Tests on the stormwater dripping from asphalt shingle roofs find that it’s remarkably clean.
Is it safe to use rain barrel water collected from your roof to irrigate homegrown lettuces, strawberries, and tomatoes?
The question is so straightforward, and yet the answer has been so murky. In the past, many sources cautioned against this use of stormwater runoff, while some, including Seattle Public Utilities, suggest it’s OK with water collected from some roof types but not others.
As rain barrels proliferate and climate change squeezes summer water supplies, there’s certain to be increasing interest in using roof runoff to grow vegetables and fruits. The problem is that there has been little direct research using runoff to water edibles and checking them for contamination.
Now data from Australia, where scientists used stormwater runoff to irrigate vegetables, as well as recently released results from the Washington Department of Ecology, which analyzed the pollutants washing off roofing materials, are helping resolve the rain barrel dilemma.
Based on these experiments and others, it appears that rain barrel water is safe to use on edibles, particularly if you adhere to some easy-to-follow advice to reduce exposure to bacteria and other contaminants. Unfortunately, some roofing materials—namely treated wood-shake roofing—release much higher levels of pollution than other roof types and are still too suspect to allow use of the runoff on food. But tests on the stormwater dripping from asphalt shingle roofs find that it’s remarkably clean.
So what exactly do the new data say? Let’s take a look.
Veggies irrigated in stormwater
Scientists from Australia’s University of Melbourne and the University of Monash, also in Melbourne, did experiments in which they watered a variety of vegetables with “synthetic” stormwater that was mixed to specifications that represent highly polluted runoff.
They used soils with a range of contamination to simulate the accumulation of metals that can occur in the ground over time. They grew kale, beets, and French beans, irrigating them with sprinklers over the course of 11 weeks. Then they harvested the crops and tested the beans, kale, beet roots, and greens for levels of chromium, copper, zinc, cadmium, and lead. They published their results in the peer-reviewed journal PLOS ONE in November 2014.
The scientists found that some of the samples of the French beans and the beet leaves, but not the beet root, had lead levels that exceeded Australia’s health guidelines. The kale in particular had lower levels of all of the metals, illustrating the wide variability in metal uptake among crops, and even into different parts of the same plant. They also reported that the more contaminated soils resulted in higher pollution levels in the plants.
The researchers concluded:
Our study makes it clear: irrigation with stormwater is indeed feasible, as long as appropriate crops are selected and are frequently turned over.
But perhaps the most important message to take away from the study was how safe the veggies were considering the rather massive doses of pollution that they received. The synthetic stormwater used for irrigation was brewed to worst-case-scenario levels of pollution—levels much higher than what’s likely to be washed off a Northwest roof.
A closer look at roof runoff
To better understand how much pollution is being flushed from Puget Sound area roofs into nearby waters, Washington Department of Ecology researchers did an experiment to capture the runoff coming from 14 different roof types.
At the Ecology headquarters in Lacey, Washington, researchers set up panels measuring 4-by-8 feet made of different common roofing materials, plus two glass control panels. Because roughly 71 percent of the total roof area in the Puget Sound basin is composite roofing, four of the 18 panels were covered with asphalt shingles, and one of the four composite panels also contained algae-resistant copper-containing granules.
Photo of the roof runoff experiment at the Washington Department state of Ecology. Photo of the roof runoff experiment at the Washington Department state of Ecology.
Then the researchers collected the rainwater running off the panels during 10 rain events from February to April of 2013 and from 10 more events from October ‘13 to January 2014.
They tested the stormwater for arsenic, cadmium, copper, lead, and zinc; poly-aromatic hydrocarbons (PAHs) associated with combustion and petroleum products; chemical flame retardants; and phthalates, an ingredient in plastics.
The runoff was surprisingly clean. A study published in September 2014 reported that the asphalt roofs and most of the others had metal levels lower than 1 part per billion (ppb), with lead levels from the asphalt roofs measuring around 0.06 ppb. By comparison, the stormwater used in the Australian experiments had lead levels averaging 330 ppb—that’s more than 5,000 times higher than the Ecology measurements.
The treated wood-shake roof, by contrast, produced high levels of arsenic (1,385 ppb), plus elevated cadmium and copper. As expected, runoff from the copper roofs also had high levels of copper.
The levels of PAHs and other organic pollutants were very low as well. Concentrations of PAHs were “generally not distinguishable from concentrations from the glass control panels, even in those roofs which have asphalt components,” Ecology reported. PAHs are produced from wood-burning stoves and auto exhaust and these air pollutants could have washed onto the roofs with the rain.
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The results from Ecology support the findings from a study published in 2013 by scientists with Rutgers Cooperative Extension. In these experiments, researchers placed 12 rain barrels at homes with asphalt shingle roofs in urban and suburban settings in New Jersey. Over the course of four months, they collected and tested the runoff. The scientists found lead and zinc levels 10 times higher or more than the Washington study, but the concentrations were still well below the level of concern and were still suitable to use for irrigating crops. In New Jersey, the amount of PAHs in the runoff was undetectable.
While both the Ecology and Rutgers experiments suggest that runoff from most roof types is low in metals and common organic pollutants, there are limitations to the Ecology study in particular. The roof on a typical house would be longer than eight feet, so the water would likely pick up more pollution running down a longer surface. Also, the test panels did not include gutters, downspouts, and flashing materials that are typically found on actual roofs and that can also leach pollutants. And the pollution levels are likely to change over time. In the two rounds of rain events, some of the pollutants decreased over time, while the PAHs appeared to increase slightly.
But even given the caveats from the Ecology study, it’s a long way to go from 0.06 ppb lead in the roof runoff in Washington to the 330 ppb in the Australian experiment, which still produced some edible veggies.
Bird droppings and bacteria
Roofs, of course, are out in the environment and depending on where you live, some mix of crows, starlings, gulls, house sparrows, and other birds are going to be flying overhead, perching on your roof, and leaving droppings behind. Birds are known to transmit disease-causing agents including E. coli and Salmonella. Add to that the waste from the occasional squirrel or rodent and there’s a good chance some bacteria or other pathogens will be added into the runoff mix.
Unfortunately, there’s little research on the question of whether roof runoff is likely to contain troublesome pathogens that pose a risk as irrigation water. While the Australian’s faux stormwater runoff included bacteria, the scientists didn’t report results regarding it. And there is research on using roof runoff for drinking water and applying sewage sludge on edibles, but it’s challenging to use that information to draw conclusions for rain barrel water and food.
Luckily, the New Jersey study did take a limited look at bacteria. The researchers started their project by tabulating total coliform, but when high bacteria levels kept coming back, they added E. coli measurements to the study partway through their data collection. When the final results were tallied, the E. coli levels exceeded New Jersey drinking water standards in 66 percent of the 47 samples collected. But when compared to the U.S. Food and Drug Administration’s standards for water used in agricultural irrigation, the rain barrel water missed the mark only 9 percent of the time.
Hedging your rain barrel bets
The fact is, the data are still less than perfect for answering all of the questions around roof-runoff and food safety. But there is good information available, and it points toward the conclusion that rain barrel water is fine for irrigation in nearly all cases. Plus, there are some straightforward strategies for further reducing your risk:
Rain barrels by Jennifer C. used under CC BY 2.0
Consider your roofing materials
Seattle Public Utilities has a rain barrel homeowners guide that gives a thumbs down to watering edibles with runoff from treated wood-shake roofs; other roofs treated with toxic agents, including chemicals to kill moss, algae, or rot; roofs with zinc strips; or roofs made of copper or with copper gutters.
Don’t collect the first “flush”
The runoff from the first couple of heavy rains after a dry spell can wash away some of the pollution and bird waste that has accumulated over times. So don’t collect this water; instead divert it straight into the ground or a storm drain.
Bleach the bacteria
Rutgers researchers suggest treating rain barrel water with bleach to kill the bacteria before using the water for irrigation. To do this, add approximately one ounce of household unscented chlorine bleach to 55 gallons of water and wait 24 hours to allow the chlorine to dissipate before applying to your garden.
Water the soil, not the food
As stormwater percolates through soil, the dirt and microorganisms living in it will help clean it. Northwest researchers demonstrated this dramatically with an experiment using salmon. They put one group of fish into stormwater runoff collected directly from a roadway and a second group in runoff after it trickled through a simulated rain garden with compost, sand, and gravel. The untreated runoff quickly killed the salmon, while the fish in the rain garden-treated water survived.
So watering the soil instead of pouring it directly on the veggies provides an opportunity for the soil to work some of its purifying magic before the water is taken up by the plants.
Wash your veggies
You were probably going to do this anyhow, but it’s a good idea to wash those raspberries, snap peas, and cherry tomatoes however tempting they are right off the vine.
Clean your rain barrel
Over time, it’s a good idea to clean your rain barrel by rinsing out any sediment that has collected. The University of Nebraska-Lincoln Extension also recommends using a solution of one-eighth cup of chlorine bleach mixed into five gallons of water, or a solution made from one-quarter cup each of castile soap and vinegar or lemon juice mixed into five gallons of water. Then rinse with clean water.
For additional rain barrel resources, check out The American Rainwater Catchment Systems Association or HarvestH2O, a forum for rainwater collecting enthusiasts. The magazine Organic Gardening also has some good tips.
Special thanks to Grace Philpy, a Redmond-based environmental engineer and expert on green-roof runoff at GeoEngineers, for her research suggestions for this post.
By Joan Allen
Originally published by the UConn Home & Garden Education Center
Collection of rain water from roofs using rain barrels is growing in popularity because of its many environmental and practical benefits. It can help the environment by diverting water that might contain contaminants away from storm drains and the natural bodies of water that those empty into. Depletion of well water can be a benefit when this non-potable water is used instead of the tap for things like washing cars, irrigation of plants, and flushing toilets. If you’re on a city/public water system, it can save money to use rain water where you can, too. But is using rain water to irrigate vegetables and fruits safe? Are there contaminants in it that could make people sick? Let’s take a look at what’s been studied.
A few universities in the U.S and abroad have done some work to look at potential contaminants in roof run-off water including heavy metals like zinc, copper, lead and others as well as bacteria such as E. coli and other pathogens. Testing done so far has shown low risk from these, but there is some. And of course, it depends on the type of roofing material, the environment (ie acid rain, urban vs. rural, etc) and possibly other factors. In one study, most of the metals tested the same in rain barrel water as in rain water before it hit the roofs, so little to no concern there. One exception was zinc, and elevated levels could lead to build up of this element in soils. At high enough levels, this can cause injury to plants and those plants should not be consumed (1). Monitor for this by having the soil tested.
While risk appears to be low, there were a few samples in studies (1, 2) where E. coli or total coliform bacterial levels exceeded official standards for some uses. Rain barrel water should NEVER be used for potable purposes such as drinking water, cooking or washing. Where do the bacteria in run-off come from? The main sources would be fecal matter from animals such as squirrels and birds that land and move around on the roof.
But if you’d like to water your vegetable garden with rain barrel water, are there ways to do it safely?
Dr. Mike Dietz, Assistant Extension Educator at UConn with expertise in water management recommends “not using roof water on anything leafy that you are going to eat directly. It would be OK to water soil/plants where there is no direct contact”. This is consistent with recommendations from other experts who suggest applying the water directly to the soil and avoiding contact with above-ground plant parts. An ideal set-up would be to hook up a drip irrigation system to your rain barrel(s). Pressure will be improved when they are full and if they are elevated. A full rain barrel can be pretty heavy, at about 500 lbs. for a 55 gallon unit, so make sure they are on a solid and stable base such as concrete blocks.
If possible, and this is done in larger collection systems automatically, don’t collect the ‘first flush’ of water off the roof. This would be the first few gallons. In a ¼” rainfall as much as 150 gallons can be collected from a 1000 ft2 roof surface (3). The first water to run off tends to have higher concentrations of any contaminants because of them building up on the roof since the previous rainfall event.
Another more practical way to minimize risk of pathogen/bacterial contamination is to treat the collected water with bleach. Rutgers University recommends treating 55 gallons of water by adding one ounce of unscented household chlorine bleach to the barrel once a month (or more often if rain is frequent). Allow this to stand for 24 hours before using the water for irrigation so the bleach can dissipate.
Apply collected water in the morning. Wait until leaves dry in the sun before harvesting. Ultraviolet light from the sun will have some disinfecting effect.
It is recommended to have the rain barrel water tested for E. coli. Be sure to follow the testing lab’s instructions for collection, storage and time sensitivity of the samples.
Thoroughly wash all harvested produce. In addition, you should always thoroughly wash your hands with warm, soapy water after they are in contact with collected water.
In summary, there are risks to using collected rain water for irrigation of food crops. In most cases, the risk appears to be low, and using the above sanitation practices can reduce risk.
- DeBusk, K., W. Hunt, D. Osmond and G. Cope. 2009. Water quality of rooftop runoff: implications for residential water harvesting systems. North Carolina State University Cooperative Extension.
- Bakacs, M., M. Haberland and S. Yergeau. 2017. Rain barrels part IV: testing and applying harvested water to irrigate a vegetable garden. Rutgers New Jersey Agricultural Experiment Station. Fact Sheet FS1218.
- Rainfall as a resource. A resident’s guide to rain barrels in Connecticut. CT DEEP.