A hidden leak can run for months before you see it
Not every leak announces itself. A pinhole in a supply line behind a wall, a slow leak under a slab or a toilet that fills itself all day can run quietly and show up only as a higher bill. Your water meter is the cheapest leak detector you own, and it takes about fifteen minutes to use.
This guide walks through a meter test, what the result means and what to do next. If you can already see water spraying or pooling, close the main shutoff and call. For the full service, see leak detection.
A fifteen minute meter test
You need no tools besides a flashlight.
- 1
Stop every use of water.
Close faucets, pause the dishwasher and washer, and make sure the ice maker and irrigation are not cycling.
- 2
Find the meter.
It is usually in a box near the street or the property line. Lift the lid and look for the leak dial or the small triangle.
- 3
Note the reading.
Write down the register numbers, or watch whether the leak indicator is turning.
- 4
Wait and compare.
After fifteen minutes with no water use, check again. Any movement means water is flowing somewhere.
A single quick test can mislead if a toilet or softener happens to cycle at that moment, so repeat it once if the result is unclear.
What the meter tells you
| What you see | What it suggests | Next step |
|---|---|---|
| No movement after fifteen minutes. | No continuous leak at that moment. | Look for intermittent causes like a toilet flapper. |
| Moves, and stops after you close the house main. | Leak inside the house. | Check fixtures, then call for leak detection. |
| Keeps moving with the house main closed. | Leak on the line between meter and house. | Call right away. |
| Moves only at certain times. | A cycling device. | Check softener, irrigation and ice maker. |
Meter moving with everything off?
Close the main and call. A plumber can start the diagnosis today.
Signs a leak is hiding behind the walls or floor
Meter movement is the clearest sign, but others help. A water bill that rises with no change in habits, a musty smell, peeling paint, a warm spot on the floor and the sound of running water in a quiet house all point to a leak. Bubbling or cupped hardwood and unexplained mold are late signs.
Take photographs and note the dates. They help your insurer and the plumber, and they show whether a problem is getting worse. Do not cut into a wall to look. Leak detection tools can narrow the location first.
What to do after a positive meter test
Act in order.
- Close the main shutoff to limit damage.
- Check the obvious fixtures first, especially toilets.
- Look at the water heater and the washing machine hoses.
- Call a plumber if the meter still moves with the main closed.
- Photograph the meter and keep your recent bills.
A leak outside the house on the meter side may be a city matter. The plumber can help you tell.
The most common hidden leaks and where they start
Hidden leaks are not evenly spread around a house. Toilets are the single most common, because a flapper that does not seal lets a thin stream run into the bowl without any noise. The second most common is irrigation, where a broken head or a cracked line can run for weeks under a lawn. After those come water heater connections, washing machine hoses and supply lines under sinks.
In older houses with metal supply pipe, pinholes in the wall are a regular source. In slab homes, a hot water line under the floor is the classic hidden leak, and it often shows up as a warm spot or a hot water bill that climbs while the pipe stays out of sight.
A useful habit is to read your meter once a month and write the number down. A steady trend is normal. A sudden step up with no change in habits is the clue that something started leaking. That habit costs nothing and has saved many homeowners from a very large bill.
Roy, UT local note: city meters and leaks
Roy City's 2024 water conservation plan says the city uses radio-read meters and reports an unmetered loss of 16.8 percent in 2023, with a leak repair budget of roughly 70,000 dollars a year. The plan shows that finding leaks is an ongoing city effort as well as a household one.
The city is generally responsible for its main up to the meter. The line from the meter to your house is typically yours. If your meter test points to that stretch, call a plumber, and if water is surfacing in the street, tell Roy City. Homes in Riverdale and Clearfield have their own utilities, so use the meter test with your own provider.
Questions people ask
Yes. A running toilet can move the meter slowly. Put a few drops of food coloring in the tank and see if color reaches the bowl without flushing.
Fifteen minutes is a good minimum. For a very slow leak, many people run the test for an hour or check the meter overnight.
The city or utility generally owns the line up to the meter. If you are unsure where your line ends, ask the utility or a plumber.
The city's 2024 water plan says it uses radio-read meters, which let the city read usage without a visit. Ask Roy City if your meter offers any leak alerts or usage data.