How Much Rain Collected From Roof

To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above.

How much rain collected from roof.

Keep in mind most rain falls over 2 3 months of a year. When you look at the numbers it s surprising how much water you can collect every time it rains. To find how much rain you can collect in an average rain year multiply this number by the average inches of rain. Gallons collected per inch of rainfall 0 62 total collecting area of roof in square feet so if you have a 1 000 square foot house you can potentially collect 0 62 1 000 620 gallons of water every time it rains an inch.

If you have 1 000 square feet of roof on your house and it rains just 1 inch you can collect 600 gallons of water to be used in your garden for washing your car or just for drop irrigation around your property. An average suburban roof of 200m 2 with such a rain fall can potentially harvest 100 000l of rainwater 200m 2 500mm 100 000l. For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain. So how can you do the math for your own roof.

1 of rain on 1 000 sf roof will yield 623 gallons roof area m2 x precipitation amount mm amount collected liters. With two inches of rain you can collect around 1 240 gallons. That s 600 less gallons you have to pay for and use from your town water supply. Rainwater collection calculation formulas and equations roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.

It isn t uncommon for an area to collect up to 350mm of rain in just one month even in rural areas.