Evaluating the "catch-can" test for measuring lawn sprinkler application rates

The effectiveness of measuring lawn sprinkler application rates using the catch-can test was evaluated. A survey of sources recommending the catch-can test for measuring application rates show that catch-can test procedures differ in the collector type, collector placement, number of collectors, and test duration. Analyses of catch-can tests were performed to address these procedural differences, with emphasis on the type and number of collectors required to provide a reasonable level of confidence in test results. The accuracy of the catch-can test generally improves as the number of randomly placed collectors increases. In order to achieve an accuracy of +/- 25% for 90 out of 100 catch-can tests, the number of randomly placed collectors required ranged from 6 to over 50 for hand-move systems, while for in-ground systems, the number of randomly placed collectors required ranged from 2 to 8, depending on the pressure and percent overlap of the water distribution pattern. As long as a reasonable number of collectors were used when performing a catch-can test, no consistent differences were observed in catch-can test results due to type of collectors when using tuna fish cans, soup cans, or coffee mugs.