Emergency Leak Detection
Leak detection finds water you can hear on the bill but cannot see in the house. Acoustic equipment, thermal imaging, and pressure isolation narrow a hidden leak to a small area before anything is opened up. Detection typically runs $350 to $800, and it routinely saves several times that in avoided demolition.
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How urgent is this? Depends on the leak rate. Active flooding is an emergency. A slow hidden leak found through a bill increase should be addressed within days, both for the water cost and because hidden moisture causes mold and structural damage.
Typical cost: $350 to $800 nationally. Detection is priced separately from repair. Simple interior leaks sit at the low end; slab and buried line detection requiring acoustic and tracer gas work runs higher. Many companies credit the detection fee against the repair if you use them for both.
Warning signs
- A water bill that rises with no change in household usage
- The water meter dial moving with every fixture closed
- Musty odor, or mold appearing on a wall or baseboard with no visible source
- Persistent damp patches on walls, ceilings, or floors
- Reduced water pressure throughout the house
- The sound of running water in a quiet house
What causes it
- Pinhole corrosion in aging copper supply lines
- Failed fittings, solder joints, or push-fit connections inside walls
- Supply lines under slabs abraded by movement against concrete
- Failed toilet flappers and fill valves, which are the single most common invisible water loss
- Irrigation system leaks, which frequently masquerade as household leaks
What to do before the plumber arrives
- Run a meter test: read the meter, use no water for an hour, read again, and note the difference
- Check every toilet by adding dye to the tank and waiting fifteen minutes without flushing
- Turn off the irrigation system entirely for a day to rule it in or out
- Gather several months of water bills so the timing of the change is visible
- Quiet the house for the appointment; acoustic detection genuinely depends on it
What the plumber will actually do
Establish that a leak exists and how large
A meter test with all fixtures closed confirms loss and quantifies its rate, which guides how aggressively to hunt.
Isolate the system
The supply is sectioned and pressure tested to determine which part of the system is losing water, separating hot from cold, interior from irrigation.
Acoustic and thermal survey
Ground microphones and listening equipment pick up the sound of escaping water; thermal imaging finds temperature anomalies where hot lines leak.
Pinpoint and mark
The leak is narrowed to a small area and marked, so any opening of wall, floor, or slab is as small as possible.
Report and quote the repair
A competent detection report says what was found, where, and what the repair options are, including whether a reroute makes more sense than a spot repair.
Leak detection FAQ
How much water can a hidden leak waste?
A running toilet alone can waste 200 gallons a day. A pinhole in a supply line under pressure can lose thousands of gallons a month while producing no visible symptom other than the bill. That is why an unexplained bill increase is worth taking seriously rather than waiting to see if it repeats.
Can I find the leak myself and save the detection fee?
You can do the useful first steps: the meter test, the toilet dye test, and shutting off irrigation to rule it out. Those three find a large share of household leaks for free. What you cannot do without equipment is pinpoint a leak inside a wall or under a slab, and guessing there means opening up drywall or concrete in the wrong place, which costs far more than the detection did.
Is thermal imaging accurate for finding leaks?
It is very good for hot water lines, where the leak creates a clear thermal signature, and much weaker for cold lines, where the temperature difference is small. That is why detection uses several methods together rather than relying on any one. A company that shows up with only a thermal camera is not equipped for cold-line work.
What if the leak turns out to be on the utility's side?
If the loss is between the street main and your meter, it is generally the utility's responsibility. Between the meter and the house, it is yours. Detection establishes which side of the meter the leak is on, which is worth knowing before you pay for any excavation.
Related services
- Slab Leak Detection and RepairLocation and repair of water lines leaking beneath a concrete foundation, using acoustic and thermal detection to minimize concrete work.
- Emergency Burst Pipe RepairA burst pipe releases water continuously until the supply is shut off. Emergency repair covers isolation, pipe section replacement, and pressure testing.
- Main Water Line RepairRepair and replacement of the buried water service line between the meter and the house, including trenchless replacement options.
- Whole-House RepipingReplacement of a home's supply piping where the existing system has reached end of life, using PEX or copper.
Emergency guides
Cost guides
- Slab Leak Repair CostWhat it costs to find and fix a leak under a concrete foundation, and when rerouting beats repairing in place.
- After-Hours Plumbing Rates ExplainedWhat the overnight, weekend, and holiday premiums actually are, and how to decide whether tonight's problem justifies paying them.
- Burst Pipe Repair CostWhat burst pipe repair costs by location and pipe type, plus the water damage costs that usually exceed the plumbing.
Common questions
- Emergency Plumbing BasicsWhat counts as a plumbing emergency, what to do first, and how to tell whether a problem can wait until morning.
- Costs and Billing QuestionsHow emergency plumbing is priced, what the premiums are, and which questions to ask before dispatch.
- Water Heater QuestionsLeaks, no hot water, strange noises, safety valves, and the repair-or-replace decision.
Related articles
- Your Water Heater Is Telling You It Is About to FailTank heaters give several months of warning before they flood a floor. The signs, in the order they usually appear.
- If Your Basement Backs Up When It Rains, Your Pipes Are FineRain-correlated sewer backups are a municipal capacity problem, not a blockage. Clearing your line will not stop it.
- The Empty House Problem: Why Seasonal Properties Fail in WinterA thermostat setting is not winterization. Why vacant properties produce the most expensive freeze damage there is.