Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Finding a Hidden Leak with the Water Meter

A two-hour no-use test that proves whether a leak exists, and roughly where
ApplicabilityHomes with a utility-read water meter and a main shutoff valve
Task time2 hr 17 min editorial estimate, not a measurement
PersonnelOne
Revisionv1 · 2026-08-03
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

A water bill that jumps for no clear reason often means a leak somewhere in the plumbing, and the reason it is easy to miss is that it can be silent: a worn toilet flapper, a cracked irrigation line, or a slow drip inside a wall. EPA's WaterSense program puts the average household's leaks at more than 9,300 gallons of water wasted a year, and some homes lose 50 gallons a day or more without anyone noticing. The water meter settles the question with no tools beyond what most households already own: read it, use no water for two hours, then read it again. If the number moved, water went somewhere. The meter's own leak indicator, a small dial, star or triangle that turns with any flow at all, will often show it happening in real time.

This page proves whether a leak exists and gets you halfway to where it is, using the home's main shutoff valve as a second checkpoint: close it, and if the meter is still moving, the leak sits between the meter and the house rather than inside it. It does not find the exact fixture — for that, see the linked pages on a dripping tap, a worn toilet flapper and a blocked drain. It does not cover a leak on the far side of the meter, in the line the water utility owns; that call goes to them.

Necessary equipment

ItemNote
FlashlightUse the flashlight to see inside the meter box.
Pen and paper, or a phoneRecord each reading before you leave the meter.
Watch or phone with a timerUse the timer to time the two-hour period.
Flathead screwdriver or meter key optionalSome meter box lids need a tool to lift.
Work gloves optionalThe gloves protect your hands from dirt and insects.

Find the Meter

Estimated 3 min

WARNING

WATCH FOR VEHICLES IF THE METER BOX IS NEAR A STREET.
A vehicle can injure you.

  1. Find the water meter for the property.
    • A common location is a meter box near the street.
    • Another common location is a meter box at the side of the house.
    • Some meters are inside a basement or a utility room.
    2m
CAUTION

LOOK INSIDE THE METER BOX BEFORE YOU PUT YOUR HAND INSIDE.
An insect in the box can bite your hand.

CAUTION

BEND YOUR KNEES WHEN YOU LIFT THE METER BOX LID.
A heavy lid can strain your back.

  1. If a lid covers the meter, lift the lid.
    • Some lids need a screwdriver or a meter key to lift.
    1m

Record the First Reading

Estimated 3 min

Multiplier printed on the meter register
Unverified — do not rely on this value
READ THE MULTIPLIER FROM THE FACE OF YOUR METER, OR ASK YOUR WATER UTILITY

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Find the register on the meter.
    • The register is the group of numbers near the top of the meter.
    • Some registers show the numbers on wheels.
    • Some registers show the numbers on a screen.
    <1m
  2. Find the leak indicator on the meter.
    • The leak indicator is a small dial, a star, or a triangle.
    • The leak indicator moves with any flow of water, even a small flow.
    <1m
  3. Record the number on the register.
    <1m
  4. Record the position of the leak indicator.
    <1m
  5. Record the time of this reading.
    <1m

Do the Two-Hour Test

Estimated 2 hr 4 min

  1. Tell the other people in the house about the test.
    1m
NOTICE

DO NOT USE ANY WATER FOR TWO HOURS AFTER THE FIRST READING.
Water use during the test gives a wrong result.

  1. Wait two hours after the first reading.
    • Do not run a faucet, a dishwasher, or a clothes washer during this time.
    • Do not run an automatic sprinkler system during this time.
    2h
  2. Return to the meter after two hours.
    2m
  3. Record the number on the register again.
    <1m
  4. Record the position of the leak indicator again.
    <1m

Read the Result

Estimated 1 min

NOTEA different number is a sign of a leak. Movement of the leak indicator is also a sign of a leak.
  1. Compare the first number and the second number.
    <1m
  2. If the number changed, water moved through the meter during the test.
    <1m
  3. If the leak indicator moved, water moved through the meter during the test.
    <1m
  4. If the number and the leak indicator both stayed still, the test found no leak now.
    <1m

Find the Side of the Leak

Estimated 5 min

NOTEThe main shutoff valve is a checkpoint for the test.
  1. Find the main shutoff valve for the house.
    • Common locations are a basement, a utility closet, a garage, or an outside wall.
    • The valve is close to the point where the pipe enters the house.
    2m
NOTICE

TELL THE OTHER PEOPLE IN THE HOUSE BEFORE YOU CLOSE THE MAIN SHUTOFF VALVE.
The valve stops water at every fixture in the house.

NOTICE

DO NOT USE FORCE ON A STUCK MAIN SHUTOFF VALVE.
A valve that does not close is a job for a plumber.

  1. Close the main shutoff valve.
    <1m
  2. Return to the meter.
    1m
  3. Look at the leak indicator.
    <1m
  4. If the leak indicator still moves, the leak is before the main shutoff valve.
    • A leak before the valve is in the meter, in the yard, or in the pipe from the street.
    <1m
  5. If the leak indicator stayed still, the leak is after the main shutoff valve.
    • A leak after the valve is inside the house.
    <1m
  6. Open the main shutoff valve.
    <1m

Decide the Next Step

Estimated 2 min

  1. If the test found no leak, do the test again on a different day.
    <1m
  2. Contact your water utility about a leak before the main shutoff valve.
    <1m
  3. Look for the leak inside the house if the leak is after the main shutoff valve.
    <1m
  4. Record the date of the test.
    <1m

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

hidden leak
Also called: phantom leak, silent leak, mystery leak, high water bill, water leak I can't find
water meter
Also called: utility meter, city water meter, house water meter
leak indicator
Also called: leak detector dial, leak detection dial, flow indicator, sweep hand, star gear, triangle dial
register
Also called: meter dial, meter reading, odometer, number wheels
main shutoff valve
Also called: main water valve, house shutoff valve, main water shut-off, whole-house valve
meter box
Also called: meter pit, water meter box, meter cover

When to use a professional

Contact your water utility if the leak indicator still moves after you close the main shutoff valve. The leak is then before the valve, on the utility side of the property.

Do not dig to find a buried pipe. Call a professional for any leak on the utility side of the meter. Call a plumber for a leak that you cannot find inside the house.

This page does not give a step to repair a leak. See the pages on a tap that drips, a toilet flapper, and a blocked drain for that work.

Common questions

How can I tell if I have a hidden water leak?

Read your water meter, wait two hours without using any water in the house or outside, then read it again. EPA's WaterSense program describes this exact test and estimates that the average household's leaks waste more than 9,300 gallons of water a year. If the number on the meter changed, water moved through the meter during that window, and since nobody used any, the only explanation is a leak. The meter's own leak indicator, a small dial, star or triangle, often confirms it faster, because it turns with any flow at all.

How do I read a water meter?

Most residential meters have two things worth looking at: the register, which is the row of numbers (on wheels or on a small screen) that tracks total water use, and the leak indicator, a small dial, star or triangle that turns whenever any water is flowing, even a trickle. You do not need to know the units it counts in to run the leak test — you are only comparing two readings taken two hours apart, so any consistent change is the signal.

Why is my water bill high when nothing looks wrong?

A leak inside a wall, under a slab, or in an irrigation line can run for weeks with nothing visible at all, and the bill is often the first sign anyone gets. EPA WaterSense notes that toilets are a frequent cause, since an old or worn flapper can let the tank refill silently without ever overflowing the bowl. The meter test on this page tells you whether a leak exists at all before you start checking fixtures one by one.

The leak detection dial is spinning with everything off. What does that mean?

It means water is moving through the meter right now, even though nothing in the house is turned on. That is the clearest possible sign of a leak, and you can skip straight to closing the main shutoff valve to work out whether it sits inside the house or before it.

How do I know if the leak is inside my house or on the utility side?

Close the home's main shutoff valve, then look at the meter again. If the leak indicator is still moving, the leak is between the meter and the valve, which usually means the service line or the meter itself, and that is your water utility's territory. If the indicator has stopped, the leak is inside the house, downstream of the valve, and the search moves to fixtures, the toilets and the water heater.

I confirmed a leak inside the house. What should I check next?

Start with the cheap, common causes: a running or silently leaking toilet flapper, a dripping tap, or a slow leak at a washing machine or dishwasher connection. This site's pages on stopping a dripping tap and replacing a toilet flapper cover the two most common sources. If you cannot find it after checking the obvious fixtures, a licensed plumber can trace a hidden pipe leak with equipment this page does not cover.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1Fix a Leak WeekWaterSense, United States Environmental Protection Agency · accessed 2026-07-29 · re-verification due 2027-01-25
  2. Tier 1Residential ToiletsWaterSense, United States Environmental Protection Agency · accessed 2026-07-29 · re-verification due 2027-01-25

Revision history

Current version 1 · updated 2026-08-03 · next review due 2027-08-03

  1. v1 · 2026-08-03First draft. Two-hour before/after meter test and household leak volume from EPA WaterSense 'Fix a Leak Week' (already registered, 2026-07-29). Toilet-flapper commonality from EPA WaterSense 'Residential Toilets' (already registered). EPA WaterSense 'Home Maintenance' was also read this session and corroborates the same two-hour method and adds the meter's usual location and the lid-removal step; it is proposed in data/sources-additions-find-a-hidden-leak-with-the-water-meter.json for the registry but is not cited in 'sources' and is not required for this record to pass the gate, since the two already-registered sources fully support the method. The leak indicator's appearance (dial, star or triangle) and the main-shutoff-valve isolation method are general, non-safety-critical descriptive content and are not attributed to a specific quoted source. No safety-critical value publishes as verified; the one specification (the meter's register multiplier) routes the reader to the meter face or the water utility. Written independently in Simplified Technical English; no source sentence was paraphrased.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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