Water Line Leak Detection
Between the utility meter and your foundation runs the one pipe nobody sees: the buried service line. When it leaks, the evidence is oblique (a bill that jumped, a meter that creeps with everything off, one soggy stripe of lawn), and the repair question is really a location question, because a dig that starts in the wrong place costs a yard.
Signs You Need This Service
Three checks point at the buried run before any instrument arrives:
- The meter moves with the house off. Close every fixture, silence every appliance, then watch the low-flow indicator: turning now means loss somewhere the house cannot see, the first half of the isolation test this page is built around.
- A green or soggy stripe. Walk the route from meter box to foundation after a dry week: ground that stays soft or grass that outperforms its neighbors along that path is worth marking before the listening starts.
- Pressure that sags at every fixture. Compare a first-floor tap against an upstairs one with everything else off: uniform weakness at both fits a supply bleeding before the house splits, a data point the locating visit wants.
- Water sounds with silence upstairs. Put an ear (or a screwdriver handle) to the main shutoff with the house silent: flow noise with nothing open is as close as a buried leak comes to speaking.
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This page covers finding leaks in that buried run specifically. Leaks inside the house (slab, walls, fixtures) belong to the water leak detection and slab leak pages, and fixing the located line is the water line repair page's work.
How a Plumber Diagnoses the Problem
How the location gets named:
- Isolate which side leaks. Shutting the house valve splits the system: if the meter still moves, the loss is in the buried run; if it stops, the leak is indoors and this page hands off. One valve, one answer.
- Listen along the path. Acoustic ground microphones walk the line's route, reading the leak's turbulence through soil; the loudest point, cross-checked from both directions, marks the candidate.
- Trace and confirm. Where soil, depth or noise defeat listening, tracer-gas testing (a safe helium or hydrogen mix introduced into the line) surfaces at the breach and pins it within a shovel's width. The line's route itself is located and marked first, not assumed.
- Deliver a dig spot, not a guess. The finding is a marked location with depth estimate and the evidence behind it: what the repair visit opens, instead of trenching the whole run on faith.
Tools & Equipment a Plumber Uses
Why the equipment matters here: ground microphones and correlators, instruments built to hear a specific frequency band through feet of soil, are the difference between locating and guessing on a buried line.
Line locators: the service line's actual route, rarely the straight line owners assume, is traced and marked before any listening begins. Tracer gas rigs: for deep lines, quiet leaks and noisy environments, the escape route of a light gas is the leak's address.
Frequently Asked Questions
How do I check if my service line is leaking?
The meter test: turn off every fixture and water-using appliance, note the meter's low-flow indicator, then close the house-side shutoff valve. Movement that continues with the house valve closed places the loss in the buried line between meter and foundation. Movement that stops points indoors, a different page's problem.
Who is responsible for the line between the meter and my house?
In most US utilities, the customer owns everything on the house side of the meter, the buried service line included. The utility maintains up to and including the meter. It is worth confirming your utility's split before repair, and it is why this leak is a homeowner call rather than a utility ticket.
Can a buried leak really be found without digging?
That is the point of the discipline. Acoustic listening reads the leak's noise through the soil along a marked route; tracer gas gives a chemical address where sound cannot. Neither requires opening ground; the excavation happens once, at the found spot, as part of the repair.
How bad is a service line leak if the yard is the only symptom?
Worse than it looks. The line holds full street pressure every hour of the year, so even a modest breach moves serious volume, paid for on every bill, and saturated soil undermines whatever sits above it, from lawns to walkways to the foundation corner. Quiet is not the same as small.
What happens after the leak is located?
The finding goes to the water line repair page's territory: open the marked spot and repair the section, or, when the line's material and age argue against spot fixes, the repair-versus-replacement conversation for the whole run. The location work is what makes either path a surgical job instead of a trench.
Name the Dig Spot
Report the meter-test result if you have run it, where the yard shows symptoms, and the line's approximate age. The location method follows from those three answers.
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