Required roof drainage flow rate in gallons per minute 0 0104 x rainfall rate x roof area where rainfall rate is expressed in inches per hour and roof area is given in square feet.
Gallons of water from roof.
To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above.
If you capture the rainfall runoff from a storm that just produces 1 10th of an inch of rain onto a 20 by 30 foot roof you end up with a full 32 gallon container full of water with 5 gallons left over.
A typical outdoor trash can holds 32 gallons.
When you look at the numbers it s surprising how much water you can collect every time it rains.
Either way you would like to know how much rain has fallen how many gallons have come down from the skies onto your roof yard block or town.
Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water.
Easy formula to remember.
1 inch of rainfall in an hour will cover 1 sq ft.
Converting this to gallons per minute per square foot gpm ft 2.
Also outlined are the steps to build your own rain barrel to collect water from your roof and downspout for all outdoor uses like watering and cleaning.
Rainwater can be collected from the roofs using the rain water harvesting method.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.
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.
Or maybe a low pressure cell has been napping overhead and your arm is hurting from holding that umbrella while you watch your basement fill up with water.
The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area.
An online drip calculator that calculates the amount of waste from your leaky faucets.
Can you get enough water out of the gutter to make it worthwhile.
To a depth of 1 in 1 hour.
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.
The answer is definitely yes.
1 of rain on 1 000 sf roof will yield 623 gallons roof area m 2 x precipitation amount mm amount collected liters other water conservation calculators.
Take the dimensions of the footprint of your roof and convert them to inches.
A service by the american water works association.
For sample purposes a 55 gallon barrel will be used.