How Much Rainwater Does A Roof Collect

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

How much rainwater does a roof collect.

Keep in mind most rain falls over 2 3 months of a year. 1 of rain on 1 000 sf roof will yield 623 gallons roof area m2 x precipitation amount mm amount collected liters other water conservation calculators. To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above. That s 600 less gallons you have to pay for and use from your town water supply.

An average suburban roof of 200m 2 with such a rain fall can potentially harvest 100 000l of rainwater 200m 2 500mm 100 000l. Rain barrel supplies list. If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year. To find how much rain you can collect in an average rain year multiply this number by the average inches of rain.

So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall. This capacity can be calculated using the following formula. Take the dimensions of the footprint of your roof and convert them to inches. Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.

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. Annual rainfall in millimetres x roof surface area in square metres roof catchment capacity. 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.

The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area. 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. For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain.

Rainwater collection calculator in gallons. A one inch rain will collect 600 gallonsfrom a 1 000 square foot roof while 4 500 square foot lot will receive 2 800 gallons.