Sprinkler catch-cup test
Find out how much water your sprinklers really put down, how evenly, and how long to run each zone. A free catch-cup (can) test calculator.
Most people guess their sprinkler run times. A catch-cup test measures what each zone actually puts down, in about 20 minutes, with a few cups and a ruler.
How to do it: set out 8–12 identical straight-sided containers (tuna cans or plastic cups) in a grid across one zone, away from the heads themselves. Run the zone for 10–20 minutes. Measure the water depth in each container with a ruler and enter them below.
What the numbers mean
- Application rate is how fast the zone puts water down. Spray heads are usually fast (1–2 in/hr); rotors and rotary nozzles are slow (0.3–0.7 in/hr). Zones with different head types need different run times.
- Evenness (DU) compares the driest quarter of the cups with the average. At 70% or above, coverage is good. Below about 55%, some spots get less than half as much as others, and adding minutes just floods the wet spots to rescue the dry ones.
- Scheduling multiplier. Because coverage is never perfect, the run time is stretched a little so the drier areas still get enough. Better coverage means a smaller multiplier and less water.
Repeat the test for each zone: zones rarely match. Once you know a zone’s rate, the cycle-and-soak scheduler checks whether your soil can absorb it that fast.