It can be, but irrigation leaks are also common. Turn everything off, then check the water meter. If the meter keeps moving and the patch stays wet with the irrigation off, a buried water line is likely leaking. If the meter is still, look at irrigation valves, pool equipment, a cooler line or drainage.
Tell the source apart in four steps
- 1Turn the irrigation controller off. Some leaks only show while the system runs, and a stuck valve can keep a zone flowing on its own.
- 2Note whether the wet spot stays wet. Look at it after a few hours. A patch that dries out was probably from a sprinkler cycle, rain or runoff. A patch that stays soggy or grows with everything off points to a pressurized leak.
- 3Run the meter test. Turn off every water use in the house and read the meter. EPA's version is: "Check your water meter before and after a two-hour period when no water is being used. If the meter changes at all, you probably have a leak." On a digital meter, the City of Chandler says to "observe the flow rate screen for at least 10 flashes. If the number is greater than zero on any of the flashes, you have a continuous leak." Full steps are in our water meter leak test guide.
- 4Shut off the water at your home's main valve and read the meter again. If it stops, the leak is inside your house or in a line past the valve. If it keeps moving, water is leaking somewhere between the meter and your house. Chandler puts it this way: "water is flowing between the meter and the shut-off valve." In many Valley homes the irrigation line tees off before the house valve, so a leaking irrigation valve or line also keeps the meter moving.
If the meter is still with everything off, the wet spot isn't a leak on the pressurized line. Move on to the list below.
Common causes of a wet lawn
A sprinkler or drip line. This is a very common source. The City of Phoenix says: "Walk your yard. Soggy ground or sinkholes can be evidence of underground line leaks in sprinkler systems." Run each zone by hand and watch for broken heads, missing emitters, or water welling up along a line. Phoenix also warns that "trapped sand or debris can interrupt shut-off of sprinkler valves causing continuous water flow," so check valve boxes for water. EPA notes how fast a small hole adds up: "An irrigation system that has a leak 1/32nd of an inch in diameter (about the thickness of a dime) can waste about 6,300 gallons of water per month." See how to fix drip irrigation and why a sprinkler system won't shut off.
The water line to the house. This is the pipe from the meter to your house. Signs are a wet or sunken patch on the line's path, a meter that runs with everything off, and often a drop in pressure. It can leak for a long time before it surfaces, so the wet spot is often a few feet from the actual break.
Pool equipment. Backwash lines, autofill valves and pump connections all leak. Chandler notes that meter movement can be caused by "an automatic pool filler, a leaky irrigation valve, or an evaporative cooler." Phoenix says "about one in 20 pools leak." See how to find a pool plumbing leak.
An evaporative cooler or A/C drain. A cooler's supply or drain line and a condensate drain can dump water in one spot, right at the same place every day. That can look like a broken line but shows up on a schedule.
A sewer line. A leak in the drain from the house to the street usually comes with a smell or slow drains rather than a steady flow of clean water. It's a different problem with a different fix; see signs of tree roots in a sewer line.
Rain, runoff and grading. After a monsoon storm, a low spot or a downspout can hold water for days with no plumbing involved. If the wet spot appears only after rain, it's drainage.
Reading the pattern
Where the water shows up and when often points to the cause, before you test anything.
| What you see | Likely cause | Next step |
|---|---|---|
| Wet only after irrigation runs | Sprinkler or drip leak, or a stuck valve | Run each zone by hand and watch |
| Wet all day, meter moving with everything off | Buried water line | Shut off the main; see the broken line steps |
| Wet at the same spot every day, at the same hour | Cooler, A/C drain or pool autofill | Check the equipment on that schedule |
| Wet only after rain | Drainage, grading or a downspout | Fix the grading; no plumbing leak |
| Wet with a sewage smell or slow drains | Sewer line | Call a plumber with a camera |
| Wet right at or near the meter box | Meter connection, either side | See who owns it, below |
A patch near the meter deserves a second look at who owns it. The City of Phoenix says "issues on the city's side (from the street to the water meter) are the responsibility of the City and issues after the water meter are the responsibility of the homeowner." If water is bubbling up between the meter and the street, call the water department. If it's past the meter, it's yours. If the meter still moves with the main valve off even after you close the house valve, that page explains what to check next.
Two of those rows deserve a closer look because they're easy to mix up. A sprinkler leak and a water line leak can look identical from the surface. The difference is the meter: an irrigation leak stops when the controller is off and the zone valve is closed, and a service line leak doesn't. And a wet spot that shows up only in the monsoon is worth a note in your calendar. If it returns every storm, the grading probably needs work, and there may be nothing wrong with the plumbing at all.
What to do about it
- If the meter is moving and the ground is wet: you likely have a broken line. Shut off the water at the main and read the next steps in what to do about a broken water line in your yard.
- If it's a sprinkler leak: turn off that zone, and repair or replace the part. Consult an irrigation professional before you repair or replace valves, as the City of Phoenix advises, and let a qualified professional handle any backflow preventer.
- If you want a full walk-through of the yard: how to find a water leak in your yard covers what wet spots and greener grass mean.
- If you can't tell: stop guessing. Digging around a buried line without a locate can hit gas or electric.
If you're a City of Phoenix water customer and can't find it, the city offers a free water efficiency consultation. A specialist performs "a water meter read and inspection: used to identify and isolate outdoor leaks." It covers irrigation, pool and yard leaks rather than the plumbing inside your home.
If you're in Phoenix and water is running and can't be stopped, the City's emergency line is 602-261-8000. HQ Plumbing & Air finds hidden leaks with electronic leak detection so the crew knows where to dig before anyone digs. We're licensed and insured, we give free estimates, and you get the price up front. We take emergency calls 24/7.