Wet yard but no rain? Irrigation leak vs. underground water-line leak
A wet patch after dry weather may come from a sprinkler, drip line, valve, drainage route, or buried water line. The best first clue is timing: does it appear only during or after irrigation, or stay wet when every zone is off?
Go to the practical guide
Irrigation or buried supply line? Compare the clues
No single clue proves the source. Use several observations before deciding who should inspect it.
Wet only after a zone runs
Walk that zone and inspect heads, drip tubing, valve boxes, and overspray. An irrigation professional is often the right first call.
Wet between cycles
Check whether a valve seeps after shutoff or irrigation piping remains pressurized. Persistent moisture can also come from drainage or a buried supply line.
Wet along meter-to-house route
A private service line becomes more plausible, especially with repeatable no-use meter movement. The surface wet spot may not sit directly above the failed pipe.
Meter moves with all expected use off
Recheck irrigation and automatic systems, then use the controlled meter test. Flow supports investigation but does not identify a line.
A safe field check before excavation
Note the last rain, recent landscape changes, irrigation schedule, and exactly when the patch expands. Observe each zone separately without digging near unknown utilities. EPA WaterSense recommends checking sprinkler heads, joints, and valves; pooling between cycles can point to a problem underground. If the area remains wet with irrigation off, use the other leak clues and meter behavior to guide the next test.
When to request underground line investigation
Persistent wet ground near a suspected service-line route, paired with unexplained metered use, justifies focused underground leak detection. The City of San Diego describes the owner’s responsibility from the meter toward the property, but a wet box or street needs utility assessment rather than a homeowner guess about the boundary. Keep clear of unstable ground and avoid operating utility equipment.
Related guides and next steps
Sources and further guidance
These official sources support the general guidance above. Conditions at a specific property require direct assessment.