Gallons Of Water On Roof

The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area.
Gallons of water on roof. Converting this to gallons per minute per square foot gpm ft 2. Roof area m2 x precipitation amount mm amount collected liters. Required roof drainage flow rate in gallons per minute 0 0104 x rainfall rate x roof area where rainfall rate is expressed in inches per hour and roof area is given in square feet. This means that each square foot captures about 62 gallons per inch of rain.
1 of rain on 1 000 sf roof will yield 623 gallons. For every 1 inch of rain and 1 000 square feet of roof you capture about 620 gallons of water. To a depth of 1 in 1 hour. Rainwater collection calculator in gallons.
If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year. Rainwater collection calculation formulas and equations. Rainwater can be collected from the roofs using the rain water harvesting method. In this example 600 x 240 x 1 144 000 cubic inches of water divide by 231 to get the number of gallons because 1 gallon 231 cubic inches.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall. The answer is about 623 gallons. To calculate the runoff from any given rainfall. How much will your roof be able to capture.
Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember. Take the dimensions of the footprint of your roof and convert them to inches. 1 inch of rainfall in an hour will cover 1 sq ft.