Sprinkler Leak or Main Water Line Leak? How to Tell the Difference
A soggy patch of lawn is one of the most common reasons people suspect a broken water line. Often it is the sprinkler system instead. These checks help you tell which one it is.
Referral service: Gardena Water Line Pros is not a plumbing contractor. Your call may be connected to an independent, third-party service provider who sets its own availability, pricing and terms. Read our referral disclosure.
The short answer
Shut off the irrigation system and watch the wet spot and your water meter. If the ground dries out over a day or two, the sprinkler system is the likely cause. If it stays wet and the meter keeps moving with every fixture and the irrigation off, a leak in the main water line between the meter and your house becomes more likely.
Why the two are easy to confuse
In many Southern California yards, the irrigation supply branches off the same water line that feeds the house, often near the front of the property. Sprinkler pipes, valves and the main water line can run close together under the lawn, so a leak in any of them can show up as the same soggy patch.
Clues that point to the sprinkler system
- The wet spot is near a sprinkler head, a valve box or along a sprinkler line.
- The area is wettest right after the sprinklers run.
- One sprinkler head bubbles, sprays oddly or has weak pressure.
- Water keeps trickling from a head after the zone turns off, which can mean a valve isn't closing fully.
Clues that point to the main water line
- The wet spot is along the path between the water meter and where the pipe enters the house.
- It stays wet even with the irrigation system turned off.
- Your water pressure has dropped at every fixture.
- Your water bill has gone up without a change in use.
- The meter keeps moving with the irrigation and every fixture off.
See the full list in signs of a water service line leak.
A simple test you can do
- Turn off the irrigation controller, and if you have one, close the irrigation shutoff valve (often near the backflow device).
- Turn off all water use in the house.
- Watch the leak indicator on your water meter for a few minutes. Our water meter leak check explains how.
- Leave the irrigation off for a day or two and watch whether the wet spot dries.
| With irrigation off… | What it suggests | Who to contact |
|---|---|---|
| Meter stops and the spot dries | Irrigation leak | Irrigation or landscape specialist |
| Meter keeps moving and the spot stays wet | Possible main water line leak | Leak detection or a water line provider |
| Meter stops but the spot stays wet | Drainage, runoff or a neighbor's water | Check grading and nearby sources |
| Water at or inside the meter box | Utility equipment | Golden State Water |
These checks narrow things down but don't prove where a leak is. A provider can confirm it with leak detection before anyone digs.
Don't dig to find it
Gas, electric and communication lines can be buried near water and irrigation pipes. Excavators in Southern California contact DigAlert / 811 before digging.
This guide is general information, not a diagnosis. An on-site assessment by a qualified provider is the only way to know what's happening with a specific line. Gardena Water Line Pros is a referral service, not a plumbing contractor.
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Frequently asked questions
How do I know if a wet spot is a sprinkler leak or a water line leak?
Turn off the irrigation system (or its shutoff valve) and leave it off for a day or two. If the area dries out, the sprinkler system is the likely source. If it stays wet and the water meter keeps moving with all water off, the main water line becomes more likely.
Can a sprinkler leak make my water meter move?
Yes. Irrigation is usually fed from your service line, so a leaking irrigation valve or pipe can make the meter move even when the house is not using water. Shut off the irrigation supply and check the meter again.
Who fixes a sprinkler leak versus a main water line leak?
Sprinkler and irrigation leaks are usually handled by an irrigation or landscaping specialist. A leak in the buried line between the meter and the house is a job for a water line or plumbing provider. Leaks at the meter itself go to Golden State Water.
Why is my yard wet when the sprinklers are off?
A sprinkler valve that doesn't fully close, a leak in the irrigation pipe that stays pressurized before the valves, a drainage problem, or a leak in the main water line can all keep the ground wet.
Wet yard with the sprinklers off?
Call to be connected with an independent water line provider serving Gardena, when one is available.
Referral service: Gardena Water Line Pros is not a plumbing contractor. Your call may be connected to an independent, third-party service provider who sets its own availability, pricing and terms. Read our referral disclosure.