Make a useful catch-can record
Measure water depth at several positions during the same run, then keep the conditions with the numbers.
Prepare comparable collectors
Use suitable straight-sided collectors and a ruler that can read the resulting water depth. University extension guidance describes laying collectors across the area being evaluated. Label their locations on a sketch so a high or low reading can be found again. The tool’s three-collector minimum is an arithmetic input limit, not a recommended audit sample size. Minnesota’s formal zone-audit guidance uses at least 20 collectors; follow the protocol appropriate to your site.
Measure one shared interval
Use the same start and stop time for every collector. Record each depth, including a genuine zero; an empty field means a missing observation, not zero water. Add wind, pressure if actually measured and the sprinkler settings. Unequal run times cannot be averaged as a single shared test in our tool.
Keep the low point visible in a worked example
Arithmetic example only, not a sampling protocol or a field test: three readings of 0, 0.25 and 0.5 inches during 15 shared minutes average 0.25 inches, with a 0.5 inch range. Scaling that mean to a hypothetical 0.5 inch target gives 30 minutes total. The equivalent average is 6.35 mm and target is 12.7 mm, so the time stays 30 minutes after unit conversion. The zero-reading location still has no demonstrated application; inspect its cause instead of assuming that longer runtime fixes it.
Read an average with its spread
The worksheet reports the arithmetic mean, minimum, maximum and range. Its runtime scales that average to your chosen target. It does not calculate a standardized distribution-uniformity score, guarantee the driest point receives enough water or replace local watering restrictions.
Sources and exact models
- Utah State University Extension · Do your own water check ↗Primary source reviewed October 26, 2026
- University of Minnesota Extension · Auditing home lawn irrigation systems ↗Primary source reviewed October 26, 2026