Multiply the two figures together to obtain the square footage of your roof step 2 determine the percentage of water collected from each downspout p.
Runoff produced per square foot of roof.
Although this calculation is simple in principle the units can make it a headache.
However calctool s unit menus remove this issue doing all the unit conversion for you.
0 gallons per minute gpm 0 cubic feet per second cfs peak runoff volume.
Measure your house at ground level then add in the roof s overhang for greater accuracy.
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.
As an example if your overhang is 12 inches you ll add 2 feet to the overall length and 2 feet to the overall width of the house.
Use our metric system version.
Rainfall calculator english units how much water falls during a storm.
The basic calculation is a x r 231 g where a is the area of your roof in square feet r is the amount of rain in inches and g is the amount of runoff in gallons.
Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.
To calculate the runoff from any given rainfall.
Take the dimensions of the footprint of your roof and convert them to inches.
If you get about 10 inches of rain over the course of the spring and summer an average 1 360 square foot roof would yield 8 160 gallons of rainwater.
Count the number of downspouts coming from your roof.
Automatic overflow control directs water back to downspout when barrel is full.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.
0 gallons 0 cubic feet.
Roof pitches in.
Measure along the length of the house or building and along the width of the house or building in feet.
But at 20 watts per square foot a system rated to produce 2 kilowatts would cover roughly 150 square feet while a 3kw system would take up about 225 square feet.
Drainage pipe required minimum diameter.
Here you can easily find how much rainwater you can collect from you roof how much you need to remove from a courtyard or how much runoff you can expect from an area of land.
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.
0 inches per hour data source.
Divide 100 by the number of downspouts in order to obtain the percentage of water collected from each downspout.
This nominal square footage amount is then multiplied by a factor associated with the roof s pitch.
Step 1 determine the footprint of your structure f in square feet.
The answer is about 623 gallons.
You have to admit that whether you re in a drought situation or not it s hard to pass up that much of a free thing.
