A leak inside a wall, under a slab or in the buried line to your house can run for weeks before a stain shows. Your water meter does not care where the water goes; it measures everything that passes it. That makes it the cheapest leak detector you have, whether your water comes from Seattle Public Utilities, Tacoma Water, the City of Everett, Kitsap PUD, Bellevue Utilities or one of the many water districts across King, Pierce, Snohomish and Kitsap counties.
This guide covers homes on a metered public system. If you are on a private well, skip to the FAQ.
What you need and what to watch for
You need a flashlight, a phone to take photos, a screwdriver or a meter lid tool to lift the lid, and gloves. The meter box often holds spiders, standing water and mud, so look before you reach in.
Once the lid is off, you will see the meter face. Most residential meters around Puget Sound show:
- A register of numbers, like a car odometer, in cubic feet or gallons. Seattle bills in units of 100 cubic feet (CCF); other utilities use gallons or cubic feet. Your bill says which.
- A sweep hand that turns as water flows.
- A leak or low-flow indicator, usually a small red or black triangle, star or wheel. It spins with even a trickle of flow, which is why it matters most.
Some newer meters are digital and show flow on a small screen, sometimes only after you shine a light on a sensor. If yours looks unfamiliar, the utility's website usually has a picture of each meter type it installs.
Safety: do not use a wrench on any valve inside the meter box. On most systems the valve on the street side of the meter belongs to the utility, and forcing an old valve can break it. Leave the meter box valve alone unless you are shutting off water in an emergency.
Step by step: the meter leak test
Pick a time when nobody needs water for an hour, such as early evening.
- Turn off everything that uses water. Faucets, showers, dishwasher, washing machine, ice maker, water softener regeneration, irrigation timers and any hose. Make sure no toilet is still refilling.
- Watch the leak indicator for two minutes. If it is perfectly still, you have no measurable leak right now. If it moves, keep going.
- Take a photo of the full register. Write down the time.
- Wait at least an hour without using any water, then photograph the register again. Any change confirms the leak and gives you a rough flow rate.
- Find your house shutoff. It is usually where the main line enters the house: the garage wall facing the street, a basement wall, a crawl space access or a utility closet. Turn it fully closed, by hand if it is a lever or a gate valve.
- Go back to the meter. If the indicator still moves with the house shutoff closed, the leak is between the meter and the house: the buried service line, an irrigation tap before the shutoff, or a hose bib plumbed upstream. If the indicator stops, the leak is inside the house.
- Reopen the house shutoff slowly and narrow it down inside, starting with the toilets.
Narrowing it down inside the house
Most inside leaks found this way turn out to be one of a handful of things.
Toilets. Put a few drops of food coloring in each toilet tank, wait 15 minutes without flushing, and look in the bowl. Color in the bowl means the flapper is leaking. A tank that refills on its own every so often, or hisses, has a worn flapper or fill valve. These are a common source of a creeping indicator.
Irrigation. If your sprinkler system is plumbed after the house shutoff, close its own valve and retest. Irrigation lines and valve boxes leak quietly underground, especially after a winter freeze on the Eastside or in north Snohomish County.
Water heater. Look at the floor and the drain pan, and at the discharge pipe from the relief valve. A relief valve that drips or runs sends water down a drain or outside where you never see it. Our page on appliance and water heater leaks covers what happens when that water reaches the floor.
Fixtures and appliance lines. Check under every sink, behind the washing machine and behind the refrigerator. Close each fixture's own stop valve one at a time and see whether the meter's indicator stops.
Inside a wall or under a slab. If every fixture is isolated and the meter still moves with the house shutoff open, the leak is in the piping itself. Signs include a warm spot on a slab floor, the sound of running water in a quiet house, a damp baseboard, peeling paint or a musty smell. This is where you stop and call: opening walls at random does more damage than finding the leak first.
Typical costs around Puget Sound
These are typical Puget Sound ranges to help you plan, not quotes. Prices vary with the house, access, the time of day and the contractor.
- Doing the meter test yourself: your time and a flashlight. A meter lid tool, if you want one, runs roughly $15 to $40 at a hardware store.
- Toilet flapper or fill valve: roughly $10 to $40 in parts if you replace it yourself; a plumber visit for the same job is commonly $150 to $350.
- Professional leak location (acoustic listening, thermal imaging, pressure testing): commonly $200 to $600 for a house, more for slab or long yard lines.
- Repairing or replacing a buried service line from the meter to the house: often $1,000 to $5,000 or more, depending on length, depth, driveways and landscaping.
- Drying a wall or floor after a hidden leak: depends on how far the water traveled. A small closet is very different from a full kitchen.
If the hidden leak was sudden and damaged the house, the water damage may be covered under your homeowners policy even when the pipe repair is not; slow, long-term leaks are often excluded. Our guide on what is covered explains the difference. Where the claim is covered, restoration can be $0 upfront on covered claims - insurer billed directly - deductible applies. Ask your agent before assuming either way.
When to call a professional
Call a plumber or a restoration contractor, rather than continuing on your own, when:
- The meter indicator spins fast or the register moves noticeably in a few minutes. That is a lot of water going somewhere.
- The leak is in the yard line and you see a soggy patch, a sinkhole or water surfacing near the foundation. Water against the foundation can end up in a basement or crawl space; see our page on flooded basements and crawl spaces.
- The leak is inside a wall, ceiling or under a slab. A pro can find it with meters and thermal imaging and open only what is needed.
- Water is near electrical outlets, a panel or light fixtures. Do not touch anything electrical while standing on a wet floor.
- You find wet drywall, swollen flooring or a musty smell. The leak may be fixed, but the water already in the materials still has to come out. Drying to a measured standard is what our structural drying page describes.
- You cannot close the house shutoff or it will not stop the flow.
If water is actively coming into the house, close the house shutoff first and then call. Dispatch is 24/7 for all four counties at (844) 543-5757, and the water damage restoration page explains what happens when the crew arrives.
Make it a habit
Once a season, repeat the two-minute indicator check with everything off. It takes less time than reading the bill, and it catches a running toilet or a split irrigation line before the next bill or the next stain does. Before you leave for a trip, a quick look at the indicator also tells you whether it is worth closing the house shutoff while you are away.
