Leak Detection
Locate hidden water loss behind walls, under floors or along the buried pipe, then decide how small an opening can be.
Plumbing guide
How to Find a Water Leak in Your Mesa, AZ House
Most hidden leaks give themselves away to a patient search. These steps start free, take under an hour and tell you when it is time to bring in equipment.
By the Mesa Plumbing 24/7 team ·
Start with the meter
Shut off every fixture and appliance, then check the leak indicator on the water meter. If it moves, water is leaking. Note the register reading, wait two hours with no water use, and read it again.
A change in the reading confirms a leak and measures it roughly. Nothing on the indicator but a bill spike points to a seasonal cause such as irrigation.
Split the house in half
Close the house-side main valve and watch the meter. A dial that stops means the leak is inside the house. A dial that keeps moving puts the leak between the meter and the valve.
That one step saves hours of searching. It tells you whether to look in walls or in the yard.
Check the fixtures
Test each toilet with a few drops of food coloring in the tank. Look under every sink and behind the dishwasher and washer. Check the water heater, its relief pipe and the pan below.
Feel along visible pipes for dampness. Look at ceilings for stains and at baseboards for swelling or soft spots.
Meter test results at a glance
Shut off every fixture, read the meter, wait, and read it again. Then use this table.
| What the meter does | What it suggests | Next step |
|---|---|---|
| Does not move | No active leak in that window | Check for intermittent leaks like toilets |
| Small dial spins slowly | A slow leak somewhere | Close the house main and watch again |
| Stops after the main is closed | The leak is inside the house | Check fixtures, then walls and slab |
| Keeps moving after the main is closed | The leak is before the house valve | Call for a service line check |
Look at the floor and the yard
A warm spot on a slab floor can mean a hot water line is leaking beneath it. A damp patch in a gravel yard, a green stripe in dry ground or the sound of water near the meter points outside.
Photograph anything unusual with a ruler for scale so you can show it to a contractor.
Use your ears
On a quiet night, put your ear near the meter, water heater and walls where pipes run. A faint hiss or trickle with everything off is a leak.
A screwdriver pressed to a pipe with your ear on the handle carries sound better than ears alone.
When equipment is needed
Leaks inside walls, under slabs or in buried lines need listening gear, thermal imaging or a pressure test. A contractor isolates the line first, then pinpoints the spot.
Ask what methods they plan to use. The leak detection page explains how a search narrows down the problem.
Check the obvious fixtures first
Many leaks live in plain sight. Look under every sink for damp cabinet floors, swollen wood and green crust on fittings. Check the base of each toilet for water, and press on the floor around it for softness.
Run each shower and tub for a minute and look at the drain and overflow. Look at the washer hoses and the dishwasher supply line, and check the water heater base. These stops take ten minutes and explain a large share of mystery bills.
Listen and feel
With the house quiet, stand near the main line and listen for a faint hiss or the sound of running water. Walk the rooms and rest a hand on walls near plumbing runs. A wall that feels cool and damp when the others are dry is worth noting.
Floors give hints as well. A warm patch on a slab can point to a hot line, while a cold damp spot suggests a cold line. Do not cut into walls or floors on a guess. Mark the spot and tell the plumber what you found.
Outside the house
Walk the line from the meter to the house and look for wet ground, green patches or sunken soil. Check the hose bibs, the irrigation valve boxes and any pool equipment pad.
Lift the meter lid carefully and look for water pooling inside the box. A wet meter box can mean a leak on either side, so photograph it and ask which side is yours. A water line repair call covers the buried line to the house.
Dye and paper tests for toilets and drains
Add a few drops of dye to each toilet tank, wait without flushing and check the bowl. Run a sheet of dry paper towel around the base of a toilet or tub to catch small seeps.
These cheap tests rule out the most common sources. If all of them come back clean and the meter still moves, the leak is hidden in a wall, slab or buried line.
What a plumber uses that you do not
Professionals use acoustic microphones to hear a leak through pipe, thermal cameras to see temperature changes and pressure testing to isolate sections of line. Each tool narrows the search without opening the wall first.
The result is a marked spot and a plan, not a guess. That is worth more than cutting several holes hoping to hit the pipe.
Keep a simple leak log
Write down meter readings, dates and any sounds or damp spots you notice. Take photos of stains with a coin for scale. A log helps the plumber see how a leak is changing.
Share it when you call. Details such as the time of day a hiss is loudest or whether hot water use makes it worse speed up the diagnosis and save you money.
Write down what you find
Note the time you checked the meter, the dial position and which fixtures were off. A short written record helps the plumber skip steps you already ran.
Photograph any stain or damp patch next to a coin or ruler for scale. Repeat the picture a day later, because a patch that grows tells you the leak is active.
Common questions
Finding a leak questions
Look for a warm floor spot, a meter that moves and the sound of water. A contractor can locate it with listening gear.
Often yes, for toilets, sinks and visible pipe. Hidden leaks need equipment.
A little triangle, star or dial that turns whenever water moves.
The owner is responsible for pipe on the house side of the meter. If unsure, ask the City of Mesa.
Related services
Slab Leak Detection & Repair
Pinpoint a failing line under the concrete floor of a Mesa home and compare spot repair, reroute and repipe.
Water Line Repair & Replacement
Fix or renew the supply pipe running from the street meter to your house, including trenchless options.
Found a leak you cannot reach?
Call and describe it. The dispatcher will set up a visit.