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Rainwater Harvesting Q&A

Q: How is rainwater captured?

A: Rainwater can be directed by gutters and downspouts to cisterns to store water or more simply by earthworks. Creating earthworks is the practice of building berms or contouring slopes on a site to guide rainwater to trees and shrubs.

Q: How much rain can the desert really supply?

A family of three in Tucson uses an annual average of 120,000 gallons of water. With about 12 inches of rainfall per year in this region, a quarter-acre lot will receive, on average, 67,000 gallons of rain water annually-- more than enough to satisfy home exterior needs if the rainwater is kept onsite. The yearly rainfall a house of 2,000 square feet could capture is about 15,000 gallons, which could potentially be stored for use in dry seasons. Click here for rainwater capture calculation help.

Q: How does rainwater harvesting make a difference?

Harvesting rainwater enhances the region’s limited water supply and offsets water use and demand. Since over a third of residential potable water use goes to landscaping, switching to rainwater for vegetation needs is a simple way to reduce potable water use. Conservation of resources ensures their availability for the environment, as well as for future generations. 

Q: Is rainwater safe to drink?

Rainwater must be purified before it is safe for human consumption. The
NSF International Rainwater Catchment System Testing Program uses U.S. Environmental Protection Agency health guidelines to review rainwater harvesting materials to ensure they do not contaminate captured rainwater. Filtration is not necessary to irrigate plants or for other non-potable uses such as flushing toilets, washing clothes, and supplying water cooling towers. 
Q. Do I need approval to set up a rainwater harvesting system?

A. For information about regulations and incentives, please click
Q: How expensive is it to harvest rainwater?

For the cost of a shovel, you can passively harvest rain by making sure stormwater is directed to plants and does not run off your property. Covering soil with mulch is one of the most effective ways to store water for your vegetation. Reduced water use will reduce the energy required for pumping potable utility water and save you money. Take advantage of your current resources and begin to see your roof as the top of your own personal watershed. Invest your time in observing the slope of the land, noticing where you can create depressions to slow down runoff and put it to beneficial use.
If you are ready to do more, you can connect your gutters and downspouts to cisterns, which can vary in price from under $50 for a 50-gallon barrel to several thousand dollars for larger tanks. Local resources exist for pre-made cisterns in a large price range or you can find materials to make your own for under $1,000. The Metropolitan Pima Alliance estimates a cost of $2 to $4 per gallon for a cistern system. 
Community workshops and cooperatives are available for you to learn how to install storage tanks yourself. Alternatively, local technicians are available in the region to help you install a cistern.

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