Garden & outdoors
Sprinkler catch-can analysis
Calculate catch-depth uniformity and application rate from your measurements.
A clear answer. Here’s how.
For equal-area evenly spaced catches, reports mean depth, lowest-quarter mean, DU = lower-quarter/overall mean, and Christiansen CU = 1 − sum absolute deviations/(N × mean), as percentages. Mean rate is depth × 60/test minutes. Requires 4–1,000 measurements in multiples of four so the quarter is exact. CU is not clamped and can be negative. Not the area-weighted pivot method.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Equal-area collected depths (mm)
- 8, 9, 10, 11, 7, 9, 10, 8
- Test duration (minutes)
- 15
Example result
- Mean depth (mm)
- 9
- Lower-quarter mean (mm)
- 7.5
- Lower-quarter distribution uniformity (%)
- 83.3333333333
- Christiansen uniformity coefficient (%)
- 88.8888888889
- Mean application rate (mm/h)
- 36
Equal-area, evenly spaced catches only, not pivot area-weighting. DU uses the lowest quarter; CU is un-clamped and can be negative for very uneven samples.