Leak Detection
Trace a hidden leak behind a wall, under a slab or along the buried line before any wall has to be opened.
Homeowner tips
Finding a Hidden Water Leak in a Colorado House
Shut off every fixture and watch the water meter. If the dial or the leak indicator keeps moving, water is leaking somewhere between the meter and the fixtures.
By the Westminster Plumbing Co. team ·
The meter test comes first
Turn off every tap, the ice maker, the washing machine and the sprinkler controller. Look at the meter register and the small leak indicator, often a tiny triangle or dial. Note the numbers, wait an hour and read again.
If the numbers change or the indicator spins, water is leaving the system. If the dial stays put, the leak may come and go, or a fixture may run only at certain hours.
Use the city's alert
Westminster says a possible leak alert means the meter registered continuous water use for 24 hours straight. If nothing in the house runs that long, take the alert seriously. Alerts come by email, postcard or letter.
After a repair, the city's customer portal shows hourly use, which confirms the leak actually stopped. That is a handy way to check your work.
Test the toilets
Toilets are the most common quiet leak. Add a dye tablet or a few drops of food coloring to the tank. Wait at least ten minutes without flushing, then look in the bowl. Color means the flapper is not sealing.
A toilet that refills by itself every so often has the same problem. Replacing a flapper is a short job, covered in the running toilet guide.
Walk the house and the yard
Look for stains on ceilings, bubbling paint, warped baseboards and a musty smell. Feel floors and walls for cool or warm patches. Open the cabinet under each sink and look at the supply lines and the trap.
Outside, check the sprinkler valve boxes for water, look for a soggy stripe or a green line in the lawn and listen at the meter box. The pipe between the meter and the house is the owner's responsibility.
Where the clue points
Match the clue to the likely source before you call.
| Clue | Likely source | First check |
|---|---|---|
| Meter moves with everything off | A leak somewhere on the system | Close the main valve and watch again |
| Meter stops with the main closed | A leak inside the house | Test toilets and walk each room |
| Meter still moves with the main closed | A leak between the meter and the valve | Look at the yard and the entry point |
| Stain grows after showers | A drain leak | Check the trap and the tub drain |
Is it the supply or the drain?
A supply leak runs all the time, so a stain grows even when no one uses water. A drain leak shows up only while water goes down it, so a stain appears after a shower or a load of laundry.
Condensation can mimic both. Cold pipes in a humid basement drip in summer. That is not a leak, and a meter test tells the difference.
When to call a plumber
Call when the meter moves with everything off and you cannot find the cause, when a stain keeps growing or when the leak is behind a wall or under a slab. A contractor can isolate sections of pipe and use listening gear and thermal cameras to find the spot.
If water is spreading, close the main valve first. Ask the city about its leak credit after the repair, since it has conditions and a deadline.
Clues you can read without tools
Some leaks announce themselves. A musty smell in a closet, bubbling paint, a warm spot on the floor or the sound of running water when everything is off all deserve a closer look. Warm floor patches can point to a leak in a hot water line under the slab or in the floor.
Look at the lowest points of the house too. Water follows gravity, so a damp basement corner or a stain on the ceiling below a bathroom may sit well away from the real source. Trace the stain upward and sideways before deciding where the pipe is.
How a plumber narrows it down
A professional starts with the same meter test, then isolates sections. Closing valves one at a time shows whether the loss sits on the house side, the yard line or a single branch. That process turns a whole-house mystery into one short stretch of pipe.
From there, listening gear picks up the hiss of pressurized water, and thermal cameras show warm or cool paths behind surfaces. Tracer gas can find a leak in a line that is buried or sealed. The goal is to open the smallest possible hole when the repair begins.
Leaks outside the walls
Not every leak sits indoors. A sprinkler zone with a cracked pipe, a hose bib that drips inside its box or a service line with a pinhole can all push the meter forward while the house stays dry. Walk the yard after the meter test and look for soft, green or sunken ground.
Listen near the curb stop and the meter box. A faint hiss in a quiet moment, especially at night, is a good sign of pressurized water escaping. Mark the spot and tell the contractor, since it saves time during the locate.
Keep a record for the contractor
Write down the meter readings, the time you took them and what was running. Add photos of stains and the dates you first noticed them. A clear record shortens the diagnosis and supports any insurance claim or utility adjustment.
Common questions
Answers about water leak
More than most people expect. A running toilet or a slow drip can add up to many gallons a day. The meter shows the total.
Common spots include supply connectors, toilet flappers, heater fittings, irrigation lines and the underground pipe that runs from the meter to the foundation.
Westminster describes a leak credit that applies once a year when usage runs well above average and the leak is fixed. Confirm the current terms with the utility.
Often yes. A plumber isolates the pipe, listens for escaping water and scans with a thermal camera to narrow the spot.
Related services
Water Line Repair & Replacement
Fix or replace the buried supply pipe running from the meter to your foundation.
Water Damage Restoration
Dry and rebuild a home after a pipe leak, a frozen-pipe burst or a sewer backup.
Keep reading
Reasons your water bill jumped
A bill that suddenly climbs normally traces back to just a few culprits. Check the meter, the toilets and the sprinkler before you call.
Running toilet: how to find and fix it
A toilet that runs on and off wastes water all day. A dye test finds the leak, and most fixes cost little.
Shutting off the main water valve
Know where the main valve is before you need it. This guide covers where to look, how to turn it and what to do if it sticks.
Meter still moving?
Close the main valve if water is spreading and call. Say what the meter and the rooms are doing.