Measuring Your Sprinkler's Water Use

Take 15 minutes today to see how long it takes your sprinkler to water an inch and you'll be set to water efficiently all summer long!

One of the reasons many people overwater is because they don't know how much water their sprinkler or other watering system uses.The good news is that you can easily figure this out if you have two tuna (or similarly shaped) cans, a ruler, 15 minutes, and some basic math skills.

Once you know this, you can use the Weekly Watering Number to adjust how much (or little) you water your landscape or garden each week throughout the summer.

Here's how:

  1. Place two tuna cans at two different places within your sprinkler’s spray range and run your watering system for 15 minutes. 

  2. Use a ruler to measure the depth of the water in your cans and then take the average between the two. (The amount of water in a sprinkler's spray pattern will vary depending on how close you place your cans. You can find the average by adding the amount of water in each can and divide that amount by two).

  3. Now you have the average amount of water that your watering system puts out in 15 minutes. Use this chart to see how much time it will take you to water one inch.(Grass needs about an inch of water per week during the summer to be healthy, and other plants typically use less than this. Of course, the exact amount of water needed for all plants varies with the weather and that is where the Weekly Watering Number comes in!).

Average water
depth after
15 minutes
  Total time needed
to water
1 inch
1/8" = 120
1/4" = 60
1/2" = 30
3/4" = 20
1" = 15

Can this be used for other types of watering systems?

Yes. For soaker hoses, you will need to place your cans in two locations along your hose. For drip systems, you will need to place a can at each type of emitter that your system uses (Drip systems use gallons per hour based on the type of emitter that is connected to your system, and you can check each type of emitter by checking the number stamped on each emitter e.g. 1GPH).

Watch this video to see how to use a tuna can or watering gauge to measure your sprinkler's water use:

Take the next step:

If you have an automatic sprinkler system, you will need to program this base schedule into your sprinkler’s controller.  Then you can use the Weekly Watering Number to fine tune your system’s settings to water your landscape as efficiently.


¹   An established lawn needs about 1 inch of water each week and more during hot, dry spells.  However, water needs vary from plant to plant, so it is best to check with your local garden center or landscape professional on your plant’s specific watering needs.
²  If run-off occurs, you will need to run your sprinkler for a shorter time period so that you are applying only the amount of water that your soil can absorb. Use tuna cans or watering gauges to figure out how much water your system distributes during this time, and then figure out how many times you will have water each week to put down the recommended 1 inch per week.