How Much Rain Water Will Roof Collect

Roof area m2 x precipitation amount mm amount collected liters.

How much rain water will roof collect.

Most states have shifted their laws in favor of private rainwater harvesting. An average suburban roof of 200m 2 with such a rain fall can potentially harvest 100 000l of rainwater 200m 2 500mm 100 000l. 1 of rain on 1 000 sf roof will yield 623 gallons. Collected rainwater may be used to irrigate outdoor lawns plants or gardens.

For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain. It isn t uncommon for an area to collect up to 350mm of rain in just one month even in rural areas. The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area. Rainwater harvesting is collecting the run off from a structure or other impervious surface in order to store it for later use.

To comply with colorado water law the container must be equipped with a sealable lid. 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. Colorado the state with arguably the strictest rainwater harvesting laws passed a bill in 2016 allowing for the collection of rainwater with a 110 gallon maximum capacity. Rainwater collection calculation formulas and equations.

Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water. To calculate the runoff from any given rainfall. So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall. 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.

To find how much rain you can collect in an average rain year multiply this number by the average inches of rain. Traditionally this involves harvesting the rain from a roof. If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year. Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.

When you look at the numbers it s surprising how much water you can collect every time it rains. Take the dimensions of the footprint of your roof and convert them to inches. Any container capable of collecting the rain shedding from a roof or patio can be used as a rainwater harvesting system. The rain will collect in gutters that channel the water into downspouts and then into some sort of storage vessel.

Keep in mind most rain falls over 2 3 months of a year. Rainwater can be collected from the roofs using the rain water harvesting method. The answer is about 623 gallons.