An irrigation audit is useful only when its measurements are read in the right order. Changing a controller schedule before locating a coverage, pressure, or leak problem can add water to the wrong place and make the original problem harder to see.
Read the audit as a chain: first confirm that water reaches each zone, then compare how evenly it is applied, then decide whether the amount and timing match the soil and plants. Keep the original controller program written down until the checks are complete so any change can be traced.
Start with the audit scope
Identify which zones were measured, when the measurements were taken, and what was running elsewhere on the property. A flow or pressure reading taken while a washing machine, hose, or another irrigation zone was active may not describe normal operating conditions.
Separate the result into the zone type. Spray heads, rotors, drip tubing, and tree bubblers should not be compared by minutes alone. Their output patterns and practical precipitation rates are different.
| Audit item | What it describes | Decision it supports |
|---|---|---|
| Static pressure | Supply pressure with irrigation off | Whether the incoming supply may be limited |
| Running pressure | Pressure while a zone operates | Whether the zone has enough pressure for its equipment |
| Flow rate | Water available or used per minute | Whether too many heads or emitters run together |
| Catch-cup depth | Water collected across a sprinkler zone | Coverage uniformity and precipitation rate |
| Leak or runoff notes | Water lost before reaching roots | Repair or cycle-and-soak work before scheduling |
Read coverage before runtime
Look for the driest and wettest collection points, not only the average amount. A zone can apply the correct average depth while leaving one strip dry and another strip saturated.
If one or two cups are much lower than the rest, inspect the nearby head for a blocked nozzle, incorrect arc, tilted riser, plant obstruction, or damaged fitting. If the entire far side of a zone is low, compare pressure at the source and near the end of the run before changing controller time.
Uniformity matters because a longer runtime only gives the wet areas more water. Correct obvious distribution problems first, then repeat the measurement on the repaired zone.
Compare application rate with soil intake
The audit may report precipitation rate in inches per hour or millimeters per hour. Treat that value as the speed at which the system adds water, not a recommendation for how much a plant needs.
Clay soils and slopes often accept water more slowly than a sprinkler zone applies it. Puddling, water crossing a sidewalk, or runoff at the bottom of a hill indicates that a long continuous cycle is too fast for that zone even if the weekly total is reasonable.
Use cycle-and-soak in that situation. Divide one long run into two or more shorter runs with an interval between them. The total may stay the same initially; the purpose is to let water enter the root zone instead of leaving the site.
Check whether the audit found a repair issue
Do not use a seasonal percentage adjustment to compensate for broken hardware. Repair or isolate the defect, then retest.
| Finding | Do this first | Do not do this first |
|---|---|---|
| Wet valve box or unexplained meter movement | Investigate a leak or valve that is not closing | Add runtime to a dry-looking area |
| Low pressure on all zones | Check supply demand, shutoffs, filter, and service conditions | Fit larger nozzles |
| Low pressure only at the last heads | Check zone flow, pipe size, elevation, and leaks | Lengthen the schedule |
| Missed strips next to working heads | Adjust spacing, arc, level, and nozzle condition | Water the whole zone longer |
| Runoff before root depth is wet | Use shorter cycles and a soak period | Increase a single cycle |
Translate the result into a schedule change
Once water is distributed evenly and the zone can run without visible loss, use the audit to set a measured baseline. For sprinklers, divide the target application depth by the measured precipitation rate to estimate total run time. For drip, verify moisture at root depth and use emitter flow, plant spacing, and soil response as the starting point.
Make one change at a time. Change total runtime, start times, or watering days separately whenever possible. A record that says “20 minutes to 16 minutes, two days per week, after 0.45 inches per hour measured” is far more useful than a controller setting with no context.
Verify at the root zone
Check soil several inches below the surface after the next scheduled cycle. Surface mulch and dry topsoil can be misleading: roots may be adequately moist below, or water may be pooling under a shallow wet layer.
Inspect both the fastest-drying and slowest-drying locations in the zone. If plants, soil, and coverage agree with the audit, keep the new setting for several cycles and review it again after meaningful weather changes.
Audit-reading checklist
- Confirm the measured zone, equipment, timing, and water demand conditions.
- Repair leaks, clogged filters, damaged heads, and pressure faults before changing minutes.
- Correct uneven coverage before using the zone average to set runtime.
- Use cycle-and-soak when the application rate exceeds soil intake.
- Record each schedule change and check root-zone moisture after it runs.
References
- EPA WaterSense (U.S. Environmental Protection Agency)
- USDA NRCS: Irrigation (U.S. Department of Agriculture)
- Irrigation Association (Irrigation Association)