How Much Rain Water Will My Roof Collect

So how can you do the math for your own roof.

How much rain water will my roof collect.

Concrete tile may leave you with alkalinity in your water but this isn t necessarily a problem. 0 623 gallons easy to remember formula. If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year. With two inches of rain you can collect around 1 240 gallons.

For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain. 1 of rain on 1 000 sf roof will yield 623 gallons roof area m2 x precipitation amount mm amount collected liters. To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above. 1 of rain x 1 sq.

Rain barrel supplies list. This capacity can be calculated using the following formula. Roughly speaking 1 millimetre of rain over 1 square metre of roof equals 1 litre of water. 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.

To find how much rain you can collect in an average rain year multiply this number by the average inches of rain. The measure is to take effect on aug. That s 600 less gallons you have to pay for and use from your town water supply. It isn t uncommon for an area to collect up to 350mm of rain in just one month even in rural areas.

An average suburban roof of 200m 2 with such a rain fall can potentially harvest 100 000l of rainwater 200m 2 500mm 100 000l. With over 600 gallons of high quality water available from a single inch of rain falling on 1000 square foot surface even an 85 collection efficiency estimated for clay tile will give you a lot of high quality water. Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water. When you look at the numbers it s surprising how much water you can collect every time it rains.

Annual rainfall in millimetres x roof surface area in square metres roof catchment capacity. You can use the precipitation map below to find an approximate amount for your area. Keep in mind most rain falls over 2 3 months of a year. Now most homeowners in the state are allowed to collect precipitation for later outdoor use.

1 of rainfall over 1 000 sf will yield 623 gallons to calculate the amount of rainwater you can collect you need to know your annual average precipitation for your area.