How Much Rainwater Does My Roof Collect

The collected rain must be used on the property where it is collected and may only be used for outdoor purposes such as lawn irrigation and gardening.

How much rainwater does my roof collect.

You can use the precipitation map below to find an approximate amount for your area. 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. Rain barrel supplies list. 1 of rain x 1 sq.

In 2016 house bill 16 1005 was passed allowing residents to collect rainwater from a catchment system on their rooftops into two rain barrels with a combined capacity of 110 gallons. If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year. So how can you do the math for your own roof. 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.

Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water. You can use a tarp of any size to collect rainwater but a larger the surface area the more water you ll harvest. With two inches of rain you can collect around 1 240 gallons. To find how much rain you can collect in an average rain year multiply this number by the average inches of rain.

It isn t uncommon for an area to collect up to 350mm of rain in just one month even in rural areas. 0 623 gallons easy to remember formula. Keep in mind most rain falls over 2 3 months of a year. For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain.

An average suburban roof of 200m 2 with such a rain fall can potentially harvest 100 000l of rainwater 200m 2 500mm 100 000l. To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above. Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember. 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.

If you can try to use a billboard tarp which is around 20 in 30 in 51 cm 76 cm in size to collect as much rainwater as you can. This capacity can be calculated using the following formula. Annual rainfall in millimetres x roof surface area in square metres roof catchment capacity. That s 600 less gallons you have to pay for and use from your town water supply.