Signs of a sprinkler leak
- A wet or sunken patch in the lawn that stays soggy after the zone shuts off.
- Low pressure or weak spray in one zone, or heads that do not pop up.
- A water meter that moves when every indoor fixture and the sprinklers are off.
- A jump in the water bill during irrigation season.
- Geysers, hissing or a zone valve that will not close.
How to isolate and find the leak
A broken head is the cheapest fix, and a leaking lateral or a valve is more involved. A buried main between the meter and the zones is a job for leak detection equipment, not a shovel.
| Check | What it tells you | Next step |
|---|---|---|
| Meter test with everything off | Whether water is escaping at all | If it moves, isolate the irrigation line |
| Shut the irrigation supply and watch the meter | Whether the leak is in the sprinklers or the house | If the meter stops, the leak is in the irrigation |
| Run one zone at a time | Which zone has the problem | Walk the zone for wet spots and broken heads |
| Look at the zone valve box | A leaking or stuck valve | Replace the diaphragm or the valve |
| Listen along the main line | Hissing from a leak in pressurized pipe | Call a leak detection technician |
Sprinkler or main line leak?
Shut off the irrigation supply and call. The 24/7 line is open.
Fall and winter care
Water left in irrigation lines can freeze and split pipes and fittings. Blow out or drain the system before the first hard freeze, and shut off and insulate the backflow assembly if it sits above ground.
The January 2024 winter and ice storm in the Portland metro led to heavy burst-pipe calls, according to OPB reporting, and exposed irrigation components are among the first to fail in a freeze. Spring startup is the time to check every zone before the season begins.
Repairing what you find
After any repair, run the zone and watch the meter to confirm the leak is gone. Mark the repair on a sketch of your system for next time.
Broken head or nozzle
The cheapest and most common repair. Unscrew the head, check the riser and replace the head with a matching one.
Cracked lateral pipe
A cut-out and coupling repair on the section, with new pipe and fittings. Dig carefully and call 811 first.
Leaking zone valve
A failed diaphragm or solenoid leaks into the valve box. Replacing the parts or the valve restores shutoff.
Leaking main line
A pressurized leak between the meter and the zones needs listening equipment to find, and a pro to repair.
Why finding it quickly pays
An irrigation leak is water you pay for twice, once for the water and once for the lawn you soak into mud. A small leak at a head can waste water for weeks before anyone notices, because the system runs when you are not watching.
Walk each zone once a month during the season and look for dry brown spots, soggy ground and heads that spray the wrong way. A five-minute walk catches most leaks before the bill does.
When to call a professional
A technician with listening equipment can usually find a buried leak without digging a long trench, which protects the lawn and the pipe.
- The meter moves with the irrigation off and you cannot find a wet spot.
- A zone has no pressure and the head, valve and lateral all look fine.
- You see a sinkhole or pooled water over the main line.
- The backflow assembly leaks or fails its test.
- You prefer to have a professional confirm the repair before you refill the lawn.
Simple checks you can do first
Walk each zone while it runs and look for geysers, soggy ground and heads that do not pop up. Compare the meter reading before and after a zone cycle to see which zone uses more water than it should.
Note what you find and which zone it affects. A plumber or irrigation technician can use that information to narrow the search before any equipment comes out.
One more thing to check
Seasonal care prevents many leaks. Drain or blow out the lines before a hard freeze, and open the system slowly in spring so pressure does not slam through weakened fittings.
Replace cracked heads and worn seals when you see them. A broken head can waste a surprising amount of water in a single watering cycle.
Write the zone numbers and the problem you found on the controller door, so the next person who opens it starts with your notes.
Wilsonville note: backflow assemblies and testing
State and city code require annual testing of backflow assemblies by an Oregon-certified backflow assembly tester. The city sends yearly reminder letters, and non-compliance may lead to denial or discontinuation of water service.
If your sprinkler system has a backflow assembly, that test applies, and an assembly that fails needs repair or replacement. Across the line in Sherwood, the city's building page says a backflow preventer for irrigation needs a permit, so ask your city building division before installing one. Our leak detection service finds the leak, and a line between the meter and the house falls under water service line repair. See our Sherwood page for more on that city.
Frequently asked questions
A soggy patch, weak zones, a high water bill or a meter that moves with everything off are the common signs.
Often yes, by running one zone at a time and walking it. A buried main needs listening equipment.
Water is escaping somewhere. Isolate the irrigation supply and see whether the meter stops, which tells you whether the leak is in the irrigation or elsewhere.
Before the first hard freeze of the year. Water left in lines can freeze and split them.
The city says state and city code require annual testing of backflow assemblies by an Oregon-certified tester, with yearly reminder letters. If your sprinkler system has an assembly, ask the city whether yours is on its list.