Rain Harvesting: How to Make a Rain Barrel Work for Your Garden
By Cheryl Long | Feb 3, 2010
Middle America gets hot in the summer. Try as we might to prevent that cracked-earth look in the garden, the amount of water one would use to keep a large amount of garden soil moist in July and August would be pretty pricy. Placing any number of rain barrels underneath downspouts, a bit of rain harvesting, could make all the difference for your garden irrigation expenses.
Many folks don’t realize that both topsoil and subsoil can store quite a bit of water, or that plants can then make use of that soil-stored water over time. In most areas, for much of the year, the topsoil and/or subsoil may not be saturated with water – which means there’s unused storage capacity down there. Using our design, you can enhance the effectiveness of your rain barrel by creating an irrigation attachment that will deliver rainwater from the roof to your garden or lawn in quantities that could easily double the effective rainfall in those areas – recharging the localized soil-water content in the process.
- 2-inch PVC or ABS bulkhead fitting with 2-inch female pipe thread in outer flange.
- 2-inch by 4-inches long TBE pipe nipple with 2-inch male pipe thread on both ends.
- 2-inch PVC ball valve with 2-inch female pipe thread on both ends.
- 2-inch PVC male 433-020 adapter with 2-inch male pipe thread on one end and 2-inch spigot (slip fit) on other end.
- 2-inch 672-7180manifold with 2-inch slip fit inlet and six 3/4-inch ribbed-barb outlets.
- PVC primer and PVC glue.
- Reservoir (barrel) for collecting water.
1. First, add an extension to a downspout from your house or garage to direct the runoff into a reservoir such as a barrel, large plastic water tank or stock tank – the larger the volume, the better. Or cut off a downspout so that you can fit your reservoir under it.
2. Now it’s time to make fast-flowing soaker hoses. Drill holes (about 1/16 of an inch in diameter should be sufficient) in lengths of old garden hoses and use screw-on caps to plug the ends of the hoses that will not be connected to the barrel. Alternatively, fold over and crimp the end of a cut length of hose and secure it with a hose clamp, a couple of heavy-duty staples, some scrap wire or a pop-rivet. (Note: This setup may not have enough water pressure to work with the kind of porous soaker hoses often sold in garden stores.)
3. Next, head to your local hardware store. Take a sketch to show them what you want to do (see the illustration on Page XX), and have them help you find everything you need: a bulkhead fitting (at least 2 inches in diameter) to let water flow out of a hole you’ll drill (or cut with a hole saw) in your reservoir, plus a number of PVC fittings and a section of PVC pipe to build a manifold with multiple outlets for attaching hoses to the reservoir through the bulkhead. If you would rather just order the parts for our manifold online, we’ve included a source and part numbers below.
4. Now cut a hole into the side of your barrel or tank – make it the diameter required to properly install the bulkhead fitting. (If you have a commercially made rain barrel, it may already have a small hole drilled in it with a spigot. Just carve your new hole beside that.) For holes larger than 1 inch in diameter, a hole saw connected to your hand-held drill might be best. If your reservoir is made of relatively flexible and thin plastic, you might be better off scribing the circle and carefully cutting it out with a utility knife, tin snips or keyhole saw. Place the hole near the bottom of the barrel so that as it fills with water, the pressure will push the water out through the soaker hoses. You can also use the manifold to drain the tank that way.
5. Install the bulkhead fitting, taking care to place the gasket and/or caulking so that it will seal properly.
6. Following the instructions on the PVC glue container, assemble the manifold as shown in the illustration on Page XX. Use this design as a guide – there are an infinite number of ways to create a custom manifold with PVC fittings and pipe.
7. Attach the manifold to the bulkhead fitting – be sure that the support leg on the outer end of the manifold is pointing down.
8. Attach the open ends of your hoses onto the manifold – use a hose clamp to secure them in place if the fit is loose. If the fit is too tight, use a hair dryer or heat gun to soften the hose end before slipping it over the manifold outlet barbs.
9. Place the hoses on whatever area of your garden or lawn you want to water next time it rains. If possible, rake a shallow depression into the surface of your garden rows or beds to help trap the rainwater so it will percolate into the soil and your plants’ root zones rather than just run off.
10. Wait for rain!
MOTHER EARTH NEWS Editor in Chief Cheryl Long has a knack for taking mainstream concepts and creating functionally elegant designs that preserve the earth’s precious natural resources and save money to boot.
- If you garden where too much rain is sometimes a problem, include shut-off valves on the hose outlets and a diverter on the downspout, so you can direct water from the downspout out into your yard when the garden would be harmed by excess water.
- Keep an eye on the barrel and hoses during the first few downpours. If you need the water to flow faster, drill more holes in the hoses. If the water is coming out too fast and causing erosion, tape some holes closed with duct tape.
- If you try this approach, please write to us at Editor@Grit.com and let us know how it works out for you.
Rainwater Harvesting Books
Water Storage: Tanks, Cisterns, Aquifers and Ponds by Art Ludwig (Oasis Design, May 2005; www.OasisDesign.net, 805-618-1070)
Focuses on the design of tanks for storing water, although one chapter concentrates on ponds. Includes detailed instructions for building a tank.
The New Create an Oasis with Greywater: Choosing, Building and Using Greywater Systems by Art Ludwig (Oasis Design, 5th Edition, September 2006; www.OasisDesign.net, 805-618-1070)
Covers options for using recycled greywater (water that drains from washing machines, showers, bathtubs and sinks). Plumbing, regulations and common errors are explained.
Rainwater Harvesting for Drylands (Volumes 1, 2 and 3) by Brad Lancaster (Rainsource Press, January 2006 and July 2007; www.HarvestingRainWater.com)
Volume 1 is an overview covering the basics of rainwater harvesting. Volume 2 covers the collection and storage of water in earthworks (swales, ponds and terraces), the use of mulch and greywater systems. Volume 3 (not yet published) will explore roof catchment and cistern systems in further detail.
Rainwater Catchment Systems for Domestic Supply: Design, Construction and Implementation by John Gould and Erik Nissen-Petersen (Practical Action Publishing, February 2000; PracticalActionPublishing.org or www.DevelopmentBookShop.com)
A thorough book covering both roof and ground catchment systems. All aspects of collecting and storing rainwater (in a variety of environments) are covered with illustrations, diagrams, photos and case studies. In addition to technical information, the book discusses social and economic aspects surrounding water.
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