How Much Rain Falls On Your Roof A Year

To calculate the runoff from any given rainfall.

How much rain falls on your roof a year.

For example if you have a roof that measures 1 500 square feet that equals 216 000 square inches. To find how much rain you can collect in an average rain year multiply this number by the average inches of rain. For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain. This calculation assumes a 90 efficiency.

Multiply the area of your roof by the amount of rainfall you wish to calculate for. You can enter numbers into any or all of the boxes below. It isn t uncommon for an area to collect up to 350mm of rain in just one month even in rural areas. Just multiple the square footage of roof space you have available x 0 6 gallons per square foot per inch of rain and you can see how much water you can collect from each inch of rain that falls.

1 500 x 144 216 000 multiply those 216 000 square inches by the rainfall. So if you have 2 500 square feet of roof available for water catchment and a single inch of rain falls one day we see that. Take the dimensions of the footprint of your roof and convert them to inches. When you look at the numbers it s surprising how much water you can collect every time it rains.

Average rainfall for select cities. In this example 600 x 240 x 1 144 000 cubic inches of water. Rain barrel supplies list. Keep in mind most rain falls over 2 3 months of a year.

An average suburban roof of 200m 2 with such a rain fall can potentially harvest 100 000l of rainwater 200m 2 500mm 100 000l. So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall. Use meters for areas such as your roof or yard. It is the middle of july in georgia and both you and your tomatoes are wilting in your yard both looking to the sky and hoping for rain.

Use our metric system version. Use square kilometers for large areas. Rainfall calculator english units how much water falls during a storm. The number of feet multiplied by 144 equals inches.

1500 x 0 6 x 37 1 33 390 gallons a year. Select one or more methods to choose the size of your area. To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above. If your average rainfall was 25 inches year your annual collection potential is 1 120 x.