How to Read Your Water Meter to Find a Hidden Leak
Your meter is a free leak detector. This is how to use it in about two hours.
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The short answer
Turn off all water use, read the meter, wait two hours without using any water, and read it again. If the reading changed, or the small low-flow indicator is moving, water is escaping somewhere on your side of the meter. This is the test the U.S. Environmental Protection Agency recommends to homeowners.
The test does not tell you where the leak is. It tells you whether there is one, which is the first thing worth knowing before you spend money on finding it.
What you might see on the meter
Meters differ by utility and age. These are the parts to look for.
| Meter part | What it looks like | What it tells you |
|---|---|---|
| Odometer-style register | A row of numbers like a car odometer | Total water used, usually in cubic feet or gallons |
| Sweep hand | A thin hand that turns on a small dial | Movement when water is flowing |
| Low-flow indicator | A small triangle, star or gear that spins | Spins even with a very small flow, a strong sign of a leak |
| Units label | Text such as CF, CCF or gal | One cubic foot is about 7.48 gallons, and CCF is 100 cubic feet |
| Remote reader | A digital or radio unit near the meter | May show the same numbers, or nothing at all |
Step by step
- Turn off all taps and appliances that use water, including the ice maker and irrigation
- Make sure no toilet is running and the dishwasher and washing machine are idle
- Lift the meter lid carefully, since insects can nest under it
- Note the reading or the position of the sweep hand, and photograph it
- Look at the low-flow indicator, which should be still
- Wait two hours without using water, then read and photograph the meter again
How to read the result
If the low-flow indicator is spinning at the start, you have your answer without waiting. If it is still, and the reading is the same after two hours, water is not moving through the meter, and you likely do not have a leak that runs constantly. A leak that runs only at certain times, such as an irrigation valve that opens overnight, can slip past a short test.
If the reading changed, calculate the difference and convert the units. A drop of one cubic foot is about 7.5 gallons. That gives you a sense of scale. It may be a slow drip or a serious leak.
Narrowing down where the leak is
Close the main valve at the house and check the meter again. If it keeps moving, the leak is between the meter and the house, on the service line. If it stops, the leak is inside the house. For the second case, try the toilet dye test, adding a few drops of food coloring to each tank and seeing whether color reaches the bowl. Toilets are among the most common hidden leaks in a home.
What to do with the result
A yard leak calls for water line repair. A leak in the house, in a wall or under the floor, calls for leak detection. If the leak is under a concrete slab, see slab leak warning signs for more tests. Keep your meter photos, since they are also useful for a landlord or an insurer.
If the leak turns out to be a running toilet, replace the flapper. It is often a cheap fix.
Ask your water provider
Some utilities can review your usage history or alert you to unusual use, and some can help interpret a suspiciously high bill. Call your water provider and ask what services it offers. If your meter has a remote reader or an online usage portal, the hourly usage can show a leak that runs at night.
For a bill that has jumped with no explanation, compare the last several months. A sudden step up usually means a new leak, and a slow climb points to something that has been getting worse.
Common mistakes in a meter test
- Leaving a faucet, an ice maker or a softener regeneration cycle running
- Testing while a tenant or family member is using water
- Forgetting irrigation timers that open on a schedule
- Reading a meter in the wrong units when comparing bills
- Not photographing the starting reading, so you cannot prove it changed
A quick note on readings
If the meter reads in hundreds of cubic feet, one unit is about 748 gallons, so even a single unit of change is a lot of water. If your bill uses different units than your meter, ask the utility for the conversion so you can compare like with like.
When the test says there is no leak
A clean result is still useful. It rules out a constant leak and points you to other causes of a high bill, such as more people at home, a new appliance, a filling pool or heavy irrigation. If use is up with no explanation, repeat the test at a different time of day, since some leaks only run when a valve opens or a pump starts.
Questions about this topic
The EPA suggests waiting two hours with no water use. If the low-flow indicator is spinning, you do not need to wait.
A small triangle, star or gear on the meter face that spins with even a tiny flow of water.
You need to keep water use off for two hours, so it helps to do it when nobody needs the water, such as early in the morning.
The leak may only run at certain times, or the high bill may come from higher use or a billing error. Ask your provider to review it.
Use the house main valve instead. Some utilities restrict use of the meter shutoff, so ask your provider.
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