Leak Detection
Find a hidden leak behind a wall, under a floor or between the meter and the house.
Plumbing guide
How to Find a Water Leak in Your House
A hidden leak does not announce itself. Your water meter, a little food dye and a slow walk around the house will track down many of them, and the results tell you when it is time to call.
By the Urban Comfort Plumbing team ·
Start with the water meter
The meter is the most reliable detector you have. Make sure no one is using water and that the ice maker, washing machine, dishwasher and irrigation system are not running. Open the meter box and look at the meter face. Most meters have a small leak indicator, a tiny triangle, star or dial that spins when any water is flowing, even a trickle.
If the indicator is moving, water is flowing somewhere. For a more precise test, note the register, leave everything off for two hours and read it a second time, which is the check EPA's WaterSense program recommends. A changed number means you probably have a leak. An unchanged number means the leak may come and go, or only show up when a fixture is in use.
Split the house in half
If the meter shows flow, close the main shutoff valve to the house and look at the meter again. If the indicator still turns after the house valve is shut, the loss is in the buried pipe between the meter and the house, the service line. If it stops, look inside the house.
To narrow it down, use the small shutoff valves under the sinks and toilets. Close them one at a time and recheck the meter after each. A leak that stops when a toilet valve is closed is in that toilet. A leak that remains is in the wall, the floor or another fixture.
Check the usual suspects
Toilets are one of the most common sources of hidden water loss. Add several drops of food coloring to the tank, leave it unflushed for a quarter of an hour, and look at the bowl. Tinted water there means the flapper is letting water through. Also listen for a hiss from the fill valve.
Next, check the water heater for moisture around the base, drips from the relief valve pipe and rust on the tank. Check under every sink for moisture or stains. Look at the hoses to the washing machine, the dishwasher and the refrigerator ice maker. Check outdoor spigots and the irrigation zone valves, where a stuck valve or a broken sprinkler head can run for days.
Look and listen for signs
Water stains on a ceiling, a bulging or peeling patch of paint, warped baseboards or flooring that has started to cup are signs of a leak behind a surface. A musty smell with no obvious source is another. In a closet or cabinet along a bathroom wall, look at the back for dark staining.
Listen. In a quiet house with the water off, a faint hissing, ticking or trickling in a wall or near the floor can point to a pressurized leak. Put your ear to the wall or a glass against it, though a plumber's equipment hears more.
Signs of a leak under the slab
Many Florida homes are built on a concrete slab, and some of the water lines run beneath it. A slab leak may show up as a warm spot on the floor, which suggests a hot water line, the sound of running water with all fixtures off, damp carpet or tile near a wall, or cracks in the floor. A steady rise in the water bill and a meter that will not stop are the big clues.
A slab leak is not something to repair yourself. See slab leak detection and repair to understand how it is found and the repair options.
What a plumber does that you cannot
A plumber starts by confirming the leak with a pressure test. Water supply lines are closed off in sections, and a gauge shows whether a section holds pressure. A section that loses pressure contains the leak. That is how a plumber narrows a whole house down to one wall or one stretch of slab.
After that, sensitive listening gear can hear escaping water through a floor or wall, and a thermal camera can show a cool or warm patch where a line is leaking. Some leaks are found with tracer gas, which is pushed into the pipe and detected at the surface. The aim is to open a small area, not a whole room.
Why speed matters
EPA estimates that the average household's leaks waste more than 9,300 gallons of water a year, and that nine percent of homes have leaks that waste 50 gallons or more per day. A leak does damage in three ways at once: it wastes water you pay for, it soaks materials that can rot or grow mold, and it can undermine soil under a slab or a walkway. In a humid climate, wet drywall and insulation can start to grow mold within a day or two.
If you find a leak, take photos, note the meter reading and tell your insurer early. Keep any parts and receipts. A clear record makes a claim and a repair simpler.
A note on irrigation and outdoor taps
Outdoor leaks are easy to overlook because the water disappears into the ground. Run each irrigation zone for a minute and watch for misting, geysers and puddles. Check hose bibs for drips at the handle and at the spout, and check the valve box where the zone valves live. A cracked fitting or a valve that does not close can run for days.
If the meter moves only when the irrigation timer runs, the leak is in the system and not in the house. Turn the system off at the controller and the valve until it is repaired.
When to stop and call
If the meter test shows flow and you have checked the toilets and the obvious fixtures, it is time to call for leak detection. A plumber isolates sections of pipe with pressure tests and uses listening equipment and thermal imaging to find the spot, so only a small area needs opening.
If the leak is between the meter and the house, see water line repair. If water is actively spreading, shut off the main valve first and call right away. If the structure is already wet, drying quickly limits mold, and water damage restoration covers that step.
Common questions
Finding a leak: common questions
Use the meter. With all water off, a moving leak indicator or a changed reading after an hour means water is flowing. Then check toilets, the water heater, appliances and outdoor taps.
A steady small leak can waste a lot of water over a month and damage the structure. The cost shows up in the bill and in repairs.
Close the main shutoff to the house and watch the meter. If it still moves, the leak is between the meter and the house.
Some policies cover the cost of locating a sudden leak. Many do not cover repairing worn pipe. Ask your insurer before the work.
Related services
Slab Leak Detection & Repair
Locate and fix a leak under the concrete slab that many St. Pete homes sit on.
Water Line Repair & Replacement
Repair or replace the pipe that carries water from the meter into the house.
Meter still moving?
Call and say what you found. The dispatcher will connect you with a local contractor.