Irrigation Catch Can Test
A catch can test is used to determine how long to run an irrigation system or hose-end sprinkler and how well the water is distributed over the landscape. The root zone (where water and nutrient absorbing roots grow) is typically 6 inches deep in clay soil. Usually 1 inch of water will fill this root zone, but in many cases, irrigation systems apply water faster than the ground can absorb. During a summer drought with high temperatures, the water requirement may be higher. Each type of sprinkler (spray, rotors, multi-stream rotor, drip) applies water at different rates; therefore, a catch can test is essential to determine the run time and efficiency of the system. Follow the steps below to determine the runtime of your irrigation system:
- Place 5 to 9 catch cans (tuna or cat food cans work great) in each irrigation zone or station.
- To determine how much water is applied to each area, run each zone with spray nozzles for 5 minutes; run 10-15 minutes for zones with rotors. Measure the amount of water in each catch can at the end of the specified time.
- To determine run time (time each station should run), use this example: if there is ¼ inch of water in each catch can after running for 5 minutes, to apply 1 inch of water, set the run time for 20 minutes (this is just an example; your measurements could vary greatly). Some irrigation systems apply water faster than the ground will absorb 1 inch of the water. To avoid water running off the landscape into the street, you may need to run these stations several short times instead of one long time. With this example, set the controller to run 10 minutes 2 times. (See ‘Cycle and Soak’ and ‘Aerate Lawn Area’ for more ideas.)
- If the water levels in the catch cans are equal or near equal, your irrigation system is working efficiently (distributing water evenly).
- Test each zone. Water application and distribution can vary by zone.