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Worried about overwatering your lawn? In the hottest months of summer, many homeowners worry about whether or not they are providing the right amount of water to keep their lawns healthy. That’s why you’ll want to try this DIY water measurement method, preferably soon if you’re actively watering your lawn.

The outcome of this test will determine how long you need to run your sprinkler system to provide the proper hydration without wasting water. With just a rain gauge (or a clean, empty tuna fish can) and half an hour of your time, you can be sure you’re providing your lawn with the right amount of water.

You should aim to water your lawn with one inch of water per week, unless if temperatures rise consistently above 90 degrees, in which case two inches may be necessary.

To get started, place the rain gauge in an open area on your lawn. Then turn on your sprinkler. After 15 minutes, check the amount in the rain gauge, note and then dump it. For those using a tuna fish can, stick a ruler into the can to measure the depth of the water. If at this point, puddles have not yet formed and water has yet to run off the lawn, continue watering until it begins to do so. For accuracy, you’ll want to set a stopwatch and sit out on the lawn until it reaches that point, then manually turn off your sprinkler. Or if you have a WiFi controller for your water-smart irrigation system, turn it off right from your favorite device. To calculate how long your sprinkler should run before water waste occurs, add the time on your stopwatch with the first 15 minutes. But let’s put that number aside for a minute.

So after a 15 minute timespan, how much water did your sprinkler put out? Use the chart below to determine the total amount of time you’ll need to water one inch.

Duration to Water One Inch

Water Depth* Total Watering Time
¼” 60 Minutes
½” 30 Minutes
¾” 20 Minutes
1”15 Minutes

*after 15 minutes 

Or, use this formula to determine your total water time:

15 Minutes ÷ Measured Water Depth=x

With this equation, divide 15 minutes by measured water depth to get x (your total watering time).

Now that you know your sprinkler’s output, this is the key to your optimal formula of watering deeply, but infrequently (such as twice per week). To effectively water and strengthen the root zone of the plant, water must reach a depth of three to four inches. Since Virginia’s clay-rich soil slows percolation into the soil, homeowners risk wasted runoff if they water non-stop. The solution is two or more watering cycles in the early morning, the length of which depends on your sprinkler’s output.

At the end of this DIY project you now know: 1) the total time it takes to provide one inch of water for your lawn, and 2) the total time you can run your sprinkler before water waste occurs.

It takes more time and effort to water for those with a hose connected to an above-ground manual sprinkler, but you will save on your water bill with your knowledge of the above figures. Those with an in-ground, automatic irrigation system can set specific timers to simplify the process, and a WiFi controller will further save you time and effort by allowing you to remotely control the sprinklers from your favorite device at any time.

Either way, you’re now primed to save water this summer, thanks to just a rain gauge or a tuna fish can.

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