How to Check Your Water Meter for Leaks
To check your water meter for leaks, turn off every water-using fixture, record the meter reading, wait, and read it again. Movement while nothing runs suggests water is going somewhere, but a still meter does not rule out every leak.
This guide walks through a safe, repeatable test for metered city water, including the limits that matter for Portsmouth, NH properties.
What a Water Meter Leak Test Can Tell You
A meter leak test tells you whether water is passing through the meter when nothing should be using it. That is a sign of continuous flow somewhere after the meter.
It cannot tell you where that water is going. A running toilet, a dripping outdoor faucet and a leak inside a wall can all move the meter the same way.
Use the result as one clue:
- Movement suggests continuous use or a leak downstream of the meter.
- No movement suggests no detectable flow during that test period.
- Neither result locates a leak or confirms its cause.
Find Your Meter Without Disturbing Utility Equipment
Most city water meters sit where the service line enters the building, often in a basement or utility area. Some properties have meters in an outdoor pit instead.
Look near the main shutoff valve, where the incoming pipe comes through the foundation. If you cannot find the meter, your water utility can tell you where it is.
Do not open sealed meter covers, remove wires from the meter or dig around outdoor curb boxes. Those belong to the utility.
Before You Start: Safety and Access
A meter check should be simple and dry. If reaching the meter means standing in water near electrical outlets or equipment, stop.
Before testing:
- Make sure the path to the meter is clear and well lit.
- Keep away from wet areas near electrical panels or appliances.
- Use a flashlight rather than moving stored items roughly.
- If an outdoor pit lid is heavy or damaged, leave it alone.
- Bring a phone or notepad to record readings.
If water is actively escaping, skip the test. Close your main shutoff, if you can do it safely, and get help.
Turn Off Water-Using Appliances and Fixtures
The test only works if nothing in the building is supposed to use water. Hidden demands are the most common reason for misleading results.
Turn off or pause:
All faucets and showers, indoors and out.
The dishwasher, washing machine and ice maker.
Irrigation and sprinkler timers.
Water softeners or filters during their regeneration cycle.
Humidifiers or boilers that refill automatically, if you know how to pause them safely.
Wait until toilet tanks have finished refilling after their last flush.
Read the Meter Display or Leak Indicator
Meters show usage on a dial, a row of numbers or a digital screen. Many also have a small leak indicator that moves with very low flow.
A leak indicator may be a small triangle, star or wheel on a dial meter. On digital meters, it may be a flashing symbol or flow reading.
If you are unsure what your display shows, photograph it. Your utility can help you interpret it.
Record a Starting Reading
Write down the full reading and the time. A photo is easiest and avoids misreading digits.
Note the position of the leak indicator too. Even a slight movement can matter during the comparison.
- Record the date and exact time.
- Photograph the full display.
- Note whether the leak indicator is moving now.
- List anything you could not turn off.
Wait and Compare the Reading
Wait without using any water, then read the meter again. A longer wait makes small leaks easier to see.
A short test of about 15 minutes can show steady movement. An overnight test, read at bedtime and again before anyone uses water, catches slower or intermittent leaks.
Compare both photos. Note any difference in the reading or the leak indicator’s position.
| Meter observation | What it may mean | Next check |
|---|---|---|
| Leak indicator spinning steadily | Continuous flow after the meter | Check toilets, outdoor faucets and appliances, then retest |
| Reading rose slightly overnight | Slow or intermittent use or leak | Repeat with toilets shut off at their stop valves |
| Movement stops when one fixture is shut off | That fixture or its supply line | Repair or replace that fixture component |
| Movement continues with every fixture off | Leak in supply piping after the meter | Ask about professional leak location |
| No movement during the test | No detectable flow during that period | Retest overnight if symptoms continue |
| Display hard to read or not changing at all | Meter issue or reading error | Contact your water utility |
What Continuous Movement May Suggest
Continuous movement with everything off suggests water is flowing somewhere after the meter. The most common culprits are fixtures, not pipes.
Toilets that leak into the bowl, outdoor faucets left dripping and appliances with failed valves are frequent causes. Concealed leaks in walls, floors or under slabs are possible too.
Narrow it down by closing fixture stop valves one at a time and retesting. If the meter stops after a particular valve is closed, that branch is the likely source.
What No Movement Does and Does Not Prove
No movement shows that no measurable water passed through the meter during the test. It does not prove the property has no leak.
A still meter may miss:
- Leaks that only occur when a fixture runs, such as drain leaks.
- Intermittent leaks that happened to pause during the test.
- Very slow seepage below the meter’s indicator sensitivity.
- Leaks on piping upstream of the meter.
- Non-plumbing water, such as rain or groundwater entry.
If symptoms such as damp walls or a high bill continue, the next step is investigation rather than reassurance.
Upstream-of-Meter Service-Line Leaks
A leak on the service line before the water reaches the meter may not register at all. The meter only counts water that passes through it.
In Portsmouth, the City describes the customer-owned section as running from the shutoff valve to the meter. Where the meter sits inside the building, part of that customer-owned line can be upstream of the meter.
Source: City of Portsmouth — Water Service Line Inventory, reviewed October 2026.
Signs of an upstream leak can include wet ground along the line route or water entering near the foundation. Our page on underground water line leak detection covers those symptoms.
Common Reasons a Meter Test Is Misleading
Most misleading tests come from water use the tester forgot about. A few come from reading errors.
- An ice maker or water filter refilling during the test.
- A toilet tank still refilling from its last flush.
- An irrigation timer turning on overnight.
- A household member using water during the wait.
- Reading the wrong digits, or comparing photos taken at different angles.
Repeat the test on another day before drawing conclusions.
Compare Meter Results With a High Water Bill
Meter results and bills answer different questions. The bill shows usage over weeks; the meter test shows flow during a short window.
If the meter moves with everything off and the bill is high, a leak or running fixture is a reasonable suspect. If the meter is still but the bill is high, check billing dates, estimated reads and seasonal use.
Our guide to a high water bill with no visible leak walks through billing checks in detail.
When Toilets or Irrigation Cause Confusion
Toilets and irrigation are the two most frequent sources of confusing results. Both can run silently.
A toilet flapper that leaks slightly lets water trickle into the bowl constantly. To test, close the toilet’s stop valve and see whether meter movement stops.
Irrigation systems may run on timers you have forgotten. Check whether the system has its own meter or shares the house meter, and pause it during testing.
What to Do if You Suspect an Active Leak
If you see water escaping, protect the property first. A meter test can wait.
Close the main shutoff valve, if you can reach it safely.
Stay away from water near electrical outlets or equipment.
Move valuables out of the wet area.
Photograph the water and its location.
Call for help.
If you smell gas, leave the building and call 911 from a safe place.
Portsmouth Customer-Side Water-Line Responsibility
In Portsmouth, the City states that the water system owns the service line from the main to the shutoff valve. The property owner owns the portion from the shutoff valve to the meter.
That split helps explain who to contact. It does not tell you where a leak is or who is at fault.
For a fuller explanation, see who owns the water service line in Portsmouth. Questions about meters can go to the Portsmouth Water Division at (603) 427-1530.
Meter Test Versus Pressure-Test Differences
A meter test looks for flow through the meter. A pressure test checks whether a closed section of piping holds pressure over time.
Pressure testing usually requires isolating piping and using gauges. It is generally a professional procedure, not a homeowner step.
| Method | Who typically does it | What it shows | Main limit |
|---|---|---|---|
| Meter self-check | Property owner | Whether water passes the meter while all use is off | Cannot locate a leak; may miss upstream leaks |
| Line pressure test | Plumbing professional | Whether an isolated section holds pressure | Requires isolation; shows a section, not a spot |
| Professional leak location | Leak detection provider | Approximate position of a leak, using several methods | Results depend on conditions and methods available |
How to Describe Results When You Call
Clear notes help the provider understand what you already know. Share the facts rather than conclusions.
Call (844) 442-1700 — have your meter photos and times ready, and we connect you with an independent local provider.
Useful details include:
- The start and end readings, with times.
- Whether the leak indicator moved.
- Which fixtures you shut off.
- Whether movement stopped after closing a specific valve.
- Any damp areas, stains or sounds you have noticed.
What Not to Touch on Utility Equipment
Some equipment belongs to the utility, not the property owner. Leave it alone.
- Do not break or remove meter seals.
- Do not disconnect meter wires or remote reading devices.
- Do not open or operate curb stops at the street.
- Do not dig around curb boxes or meter pits.
- Do not attempt to repair or replace the meter.
If utility equipment appears damaged or leaking, call your water utility.
Example Checklist for a Repeatable Test
A consistent routine makes results comparable over time.
Pick a time when no one will use water for at least 15 minutes.
Turn off all fixtures, appliances and irrigation.
Wait for toilet tanks to finish refilling.
Photograph the meter display and leak indicator.
Wait the full period without using water.
Photograph the meter again.
Compare readings and note any movement.
If it moved, close toilet stop valves and repeat.
Record results with the date for future comparison.
When Professional Leak Location Is Appropriate
Professional leak location makes sense when the meter keeps moving after fixtures are ruled out. It also makes sense when symptoms persist despite a still meter.
Concealed indoor leaks are covered on our hidden water leak detection page. Buried line symptoms are covered on the underground detection page.
Bring your meter notes. They can shorten the investigation.
Call (844) 442-1700 — if the meter keeps moving after you rule out fixtures, ask about professional leak location.
How Meter Checks Fit Into Prevention
An occasional meter check can catch slow leaks before they cause damage. It takes only a few minutes.
- Check after returning from a trip.
- Check after any plumbing work.
- Check when a bill looks higher than usual.
- Check after a cold snap, when pipes may have been stressed.
Keeping a simple log helps you spot changes over time.
Frequently Asked Meter-Test Questions
How long should I wait during a meter leak test?
About 15 minutes can show steady movement. An overnight test is better for slow or intermittent leaks.
If my meter does not move, am I leak-free?
Not necessarily. Leaks upstream of the meter, intermittent leaks and drain leaks may not show during the test.
What is the small triangle or star on my meter?
On many meters, that is a low-flow leak indicator. It moves when even small amounts of water pass through.
Can a running toilet move the meter?
Yes. A toilet that leaks into the bowl can move the meter steadily. Closing its stop valve during a retest shows whether it is the cause.
Should I turn off the curb stop to test?
No. Curb stops are utility equipment. Use your building’s main shutoff and fixture valves instead.
Does this test work on a private well?
Usually not. Most private wells have no utility meter, so the test is designed for metered city water.
Who do I call about my meter in Portsmouth?
The Portsmouth Water Division handles meter questions at (603) 427-1530. Confirm current hours with the City.
Call (844) 442-1700 — if your meter test points to a leak, ask about professional leak location.