National Water Center, Eureka Springs, Arkansas
         

National Water Center, Eureka Springs, AR

Updated: April 2014 Contact: Contact: NWC

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Calculations for Rainwater Catchment
by Steve Diver

Some useful figures and calculations for rain water catchment:

1.    Inches Rainfall x Square Feet of Surface Area = Amount

2.    Amount x 0.625 Factor

3.    Factor = (12-inch depth per cubic foot and 7.5 gallons per cubic foot of water) or (7.5 d        divided by    12 = 0.625)

Example: 30-inches per year is equivalent to 18.75 gallons per of water collected from each square foot of surface area.

30-inches of rainfall collected from the roof of a 1,600 square foot home = 30,000 gallons water

30-inches of rainfall collected from the roof of a 2,500 square foot home = 46,875 gallons water

Storage tank capacity will depend on total rainfall, surface area collected, seasonal rainfall patterns, and seasonal water use patterns.

If ya'll got any other handy calculations and figures, please share them.

Steve Diver, steved@ncatark.uark.edu