Gardeners Use Tuna Cans to Measure Water
When you turn on your sprinkler, it’s easy to assume that your grass is getting enough water. However, the amount of time the sprinkler runs doesn’t necessarily tell you how much water is actually reaching the grass. To get a more accurate measurement, some gardeners recommend using an empty tuna can.
Nic Gates, from the Nic Gates Show, tried this method after struggling with grass seed and lawn treatments despite using his sprinkler. He placed an empty tuna can under the sprinkler and marked the inside with a Sharpie to measure the water depth.
Gates started with a can about 1¼ inches deep and placed it under a sprinkler set to water a 90-degree section of grass. After 30 minutes, he checked the can and found that the water level was still below his mark. He considered factors like wind, low water pressure, and sprinkler performance, and decided to let the water run for another 30 minutes.
When he checked the can again, the water had reached his target. This result showed that his sprinkler took close to an hour to deliver the amount of water he wanted, twice the initial test period. This experiment shows why sprinkler runtime can be misleading, as two sprinklers can run for the same amount of time without delivering the same water depth.
How to Test Your Sprinkler
To test your sprinkler with an empty tuna can, start with a clean can and mark the inside with a waterproof marker at a height of half an inch from the bottom. Place the can upright on level grass within your sprinkler’s coverage area and turn on the water. Check the depth after 15 or 30 minutes and record how long it takes to reach the half-inch mark.
For a more accurate assessment, use several cans across the lawn, positioning them at different distances from the sprinkler. The University of Minnesota Extension recommends placing catch cans across an irrigation zone to check sprinkler coverage and measure water output.
Interpreting the Results
A low reading in the tuna can doesn’t always mean the sprinkler needs more time. Factors like poor spray coverage, blocked sprinkler heads, water pressure, and wind can affect how much water reaches different sections of grass. Comparing water depths across several cans can help identify where the sprinkler needs adjustment.
This test is especially important when watering new grass seed or applying lawn products. Some fertilizers and treatments require a specified amount of water after application, while newly seeded grass needs moisture near the soil surface during germination. Checking the product label before watering can help ensure that you’re providing the right amount of water.
