Symptoms
- Soggy or wet patch in the yard that doesn't dry out
- Water bill noticeably higher than usual
- Reduced pressure at sprinkler heads
Likely causes
- CommonCracked or loose pipe fitting undergroundPVC fittings can crack from ground shifting or freeze damage.
- CommonValve not closing fully (weeping valve)Debris in the valve seat can cause continuous slow leakage even when off.
- PossibleDamaged sprinkler head or riserA cracked head can leak water even between cycles if it's below grade.
- PossibleBackflow preventer or main line leakA leak at the main supply point causes constant water loss.
What to do
- Note whether the wet spot appears even when the system is off, which points to a valve or main line leak rather than a zone pipe.
- Check each valve in the valve box for water seeping through when it should be fully closed.
- Inspect nearby sprinkler heads for cracks, especially pop-up heads that may not retract fully.
- Dig carefully around the wet area to expose the pipe and look for a visible crack or loose fitting.
- Cut out the damaged section of pipe and replace it with a new coupling and matching PVC pipe, using primer and cement.
- Turn the system back on and monitor the repaired area over a few cycles to confirm the leak is resolved.
Tools and parts
- Shovel
- PVC cutter
- PVC primer and cement
PVC pipe couplingSearch: “PVC pipe repair coupling irrigation”
Sprinkler valve diaphragm kitSearch: “sprinkler valve diaphragm rebuild kit”
When to call a pro
A leak near the main water line or backflow preventer should be handled by an irrigation professional or licensed plumber.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.