From steved@ncatark.uark.edu Tue Oct 21 00:04:25 1997 Date: Mon, 20 Oct 1997 16:00:29 +0000 From: Steve Diver To: permaculture@listserv.oit.unc.edu Subject: Calcultations for rain water catchment Some useful figures and calculations for rain water catchment: 1st Inches rainfall x Square feet of surface area = Amount 2nd Amount x 0.625 Factor Factor = (12-inch depth per cubic foot and 7.5 gallons per cubic foot of water) or (7.5 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