# Water Q&A: How much water falls during a storm?

## Science Center Objects

Learn how calculate how many gallons of rainwater fall during a storm.

•  Water Science School HOME  •  Water Science Q&As  •

### How much water falls during a storm?

In other words, when I have a big storm over my house, just how much rain am I getting? Let's say your house sits on a one-half acre lot. And let's say you get a storm that drops 1 inch of rain. You've just received 13,577 gallons of water on your yard. A big bath holds about 40 gallons of water, so if you could save that inch of water that fell you could take a daily bath for 339 days! Let's expand that to a city. Atlanta, Georgia has corporate boundaries that cover about 84,100 acres (U.S. Census Bureau). A 1-inch rainstorm deposits 27,154 gallons on one acre, so during this storm Atlanta receives 2.28 billion gallons of water.

In this era of water conservation, many homeowners are putting "rain barrels" around their homes to collect rainfall runoff. Essentially, this is just a large bucket to collects water coming off of the roof and down the gutters and downspouts. The water is then used to water gardens and plants. Can you get enough water out of the gutter to make it worthwhile? The answer is definitely "yes". A typical outdoor trash can holds 32 gallons. 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.

You can use our handy "How much water falls during a storm" calculator to find out how much water falls during a rainstorm for a chosen sized area.