Families & Nature Feature Article

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Helping the Environment by Catching Water

By: Dr. Cathy Sabota, Horticulture Specialist

The reduction in rainfall in the Southeast since 2005 has created an increased awareness that water is not an infinite resource, and if we do not manage it correctly, it may not be there tomorrow. Rainwater harvesting is the collection and storage of rainwater for irrigation, flushing toilets, or washing cars. It is usually collected from rooftops, greenhouses, and other relatively clean surfaces (Texas Water Development Board, 2005). Most homes have gutters and downspouts plus the roof for catchment. The only additions needed are water storage containers, some additional piping, and a pump.

In the United States, each person uses more than 100 gallons of water a day for outdoor activities, including pools, hot tubs, washing the car, and for irrigating landscapes. This is more than 58 percent of our total daily water use (Mayer, et al., 2002). Landscapes are important to us. They provide shade that reduces heating, cooling bills, and increases the value of our homes by 10-20 percent. The recent drought has not only hurt our plants, but also devastated the green industry in the Southeast.

Water catchment for homeowners, plant nurseries, and high value food crop producers can reduce the effects of drought on our landscapes. It also increases farm and nursery income, reduces erosion and pollution in our lakes and streams, and assures there will be water for future generations. Rainwater harvesting offers other benefits to the community including reduced storm water runoff and reduced energy use, including a reduction of greenhouse gases compared to other large centralized municipal water systems.

Home water catchment system

The Alabama Cooperative Extension System's Urban Affairs and New Nontraditional Programs Unit located at Alabama A&M University, is aggressively promoting water catchment systems for homeowners and high value crop producers. Urban Affairs has a demonstration catchment system with a surface area (footprint) of 144 square feet. From April to December 2007, one of the driest years in history in Alabama, 1,983 gallons of water from just 22.24 inches of rain was collected. This was sufficient to support the production of 500 shiitake mushroom logs in a forest production operation.

We have also established a catchment system at Oak Mountain State Park that is 440 square feet. An inch of rain will generate 300 gallons of water or almost a complete tank of water. An inch of rainfall is sufficient to irrigate the entire ornamental landscape around the Park Office several times during the summer. This catchment system, complete with tank, pump, and plumbing, costs less than $400.

Adoption of water catchment systems, by just 10 percent Alabama households could reduce the burden of water taken from lakes and streams by 8 billion gallons of water per year. Homeowners that use catchment water are more likely to maintain their landscapes and continue to support the green industry.

The system at Oak Mountain State Park in Birmingham featured here includes 440 square feet of catchment area, which is equivalent to the office roof. Twenty feet of gutters run into a downspout to the tank that holds 264 gallons. Inside the tank is a _" PVC line with a foot valve at the bottom to keep the line from sucking to the bottom of the tank. There is also a tether float switch in the tank that turns off the pump when the tank is empty. It works like a toilet tank float valve, only in reverse. When the ball lowers in the water tank the valve shuts off, in your toilet tank the opposite happens. The pump is plugged into the tether float switch power and when the tether float switch turns off, so does the pump. Once the water is transported from the tank to the pump, it passes through a regular hose. This system has a 1 hp pump that moves 6 to 7 gallons per minute. This is enough to run a sprinkler or small irrigation system. A typical household tap would run about 8 gallons per minute. This entire system cost less than $400.

For more information about water catchment systems, please contact Extension Horticulture Specialist Dr. Cathy Sabota at 256.372.4257.

Rainwater Harvesting Systems for Montana by Gretchen Rupp (updated by Ben Cichowski), MSU Extension Service MT199707.

Vegetable Crop Irrigation by D. C. Sanders, North Carolina Cooperative Extension Service Publication No. DRO-13.

Harvesting Rainwater for Landscape Use, University of Arizona Cooperative Extension Publication No. AZ1344.

References

Mayer, P., et al. (2002). Residential end uses of water [Project #241A]. Research Topics and Projects. Retrieved November 3, 2008.

Texas Water Development Board. (2005). The Texas manual on rainwater harvesting (3rd ed). Retrieved November 3, 2008.