The main water line feeds your whole home from the meter — and when it leaks underground, the signs are a soggy yard, a climbing bill, and dropping pressure. Here’s how we find and fix it.
Written bySteven Lockhart·Reviewed byMiguel Lopez, Owner & Licensed Plumber, New Pro Plumbing (CSLB #974600)·Last reviewedAugust 2026 · 7 min readQuick Answer
A main water line leak is a leak in the underground pipe that carries water from your meter to the house. Signs include a persistently wet or soggy spot in the yard, a spiking water bill, dropping water pressure, and the sound of running water with everything off. New Pro locates the leak and repairs or replaces the line — sometimes trenchless — across West LA, 24/7.
Your main water line is the pressurized pipe that carries potable water from the meter at the street to your home. Because it is buried and under constant pressure, a leak in it runs continuously and often invisibly — surfacing as a soggy patch in the yard, an unexplained jump in your water bill, a drop in pressure throughout the house, or water pooling near the meter.
Main water line leak — Main water line leak repair is the location and repair or replacement of a leak in the pressurized underground pipe feeding a home from its meter — pinpointed before excavation.
Because it is underground and pressurized, a main line leak is a locate-first job for an emergency plumber, not something to start digging for blindly.
A slow underground leak differs from a burst pipe indoors — but both waste water fast.
A failing main line can cut pressure or, fully broken, cause no water.
Locate precisely, then repair or replace.
A meter test confirms water is escaping with everything off.
Electronic and pressure equipment pinpoints the leak underground.
We locate it from the surface to minimize digging.
A section repair, or replacement for a failing line.
We fix the leak, sometimes trenchless, and test it.
We backfill and confirm normal pressure and flow.
Leak getting worse? Shutting off your water at the main buys time — see how to shut off your water main — then call and we’ll locate the leak.
Soggy yard or a spiking bill? We locate main line leaks — call us.
Get a Free QuoteA main water line leak is one of the most expensive leaks to ignore, precisely because it is invisible and constant. Unlike a dripping faucet you can see, a buried main leak runs day and night, and the first evidence is often a water bill that has quietly doubled or a patch of lawn that stays green and soggy through a dry spell. Because the line is pressurized, even a small breach loses a surprising amount of water over a month.
The longer it runs, the more it costs — not just in wasted water, but in the damage saturated soil can do to driveways, walkways, and foundations. Catching it early, when it is still a single repairable leak rather than a failing line, keeps the fix small. The U.S. EPA’s WaterSense program highlights how much water household leaks waste nationwide, and a main line leak — running continuously underground — is among the costliest a home can have.
Because the line is buried and pressurized, this is not a dig-and-hope job. We locate the leak electronically first, then repair or replace it as licensed work you can verify with the CSLB (#974600), permitting the repair through the Los Angeles Department of Building & Safety where required. Locating first is what turns a whole-yard excavation into a small, targeted opening over the exact spot.
A single leak in a sound line is a repair; an old failing line may need replacing.
| Situation | Approach | Digging |
|---|---|---|
| Isolated leak | Section repair | Small opening |
| Aging / repeat leaks | Replace the line | Often trenchless |
| Failing whole line | Replace | Varies |
We locate before we dig and quote either option flat-rate — the way 24/7 emergency plumbing should be.
Cost depends on the leak’s depth and location, whether a section repair or a full replacement is needed, and access. Locating the leak first is what keeps the digging — and the cost — contained. A trenchless replacement can avoid trenching the whole yard. We quote flat-rate after locating.
We locate first, then quote — see how our emergency plumbing service prices flat-rate.
A homeowner's water bill doubles and a patch of lawn stays soggy in dry weather.
New Pro confirms a main line leak by meter test, pinpoints it electronically, and repairs the failed section.
The leak stops, the bill returns to normal, and the yard dries out — with a minimal dig over the exact spot.
The Bottom Line
A main water line leak is a quiet, constant drain on your water and your bill, and it will not fix itself. The signs — a soggy yard, a climbing bill, dropping pressure — are worth acting on. Locating it precisely before digging is what keeps the repair targeted, and for an old line, replacement (often trenchless) beats repeated patches.
The classic signs are a persistently wet, soggy, or unusually green patch in the yard (often over the line’s path between the meter and the house), an unexplained spike in your water bill, a drop in water pressure throughout the home, and the sound of running water when every fixture is off. A simple check is to note your water meter with everything off — if it keeps moving, water is escaping somewhere, and the main line is a prime suspect.
It is urgent, though not always a flooding emergency like a burst indoor pipe. A main line leak wastes water continuously — often a lot of it — inflating your bill, and over time the escaping water can undermine the soil, a driveway, or a foundation. It won’t resolve on its own and tends to worsen. So while you may not need a plumber at 2 a.m. for it, it should be located and repaired promptly rather than left running.
Often, yes. Once we’ve located the leak precisely, a single isolated leak may be repaired through a small opening directly over it. For a line that needs full replacement, trenchless methods can pull a new line through with only small access points rather than trenching the whole yard, avoiding most of the disruption to landscaping and hardscape. The right approach depends on whether it’s one leak or a failing line, which locating it reveals.
Generally, the homeowner is responsible for the water service line from the meter to the house (the private side), while the utility is responsible for the main in the street and up to the meter. So a leak in the buried line across your property is typically yours to repair. There can be local variations, so it’s worth confirming with your water utility, but in most cases a leak on your side of the meter is a homeowner repair.
Common causes include corrosion of older metal pipes (especially aging galvanized steel), ground movement and settling that stresses the line, tree-root pressure, high water pressure, and simple age. West LA’s older homes often have original service lines that have been in the ground for decades, and the region’s shifting soils add stress. Because the cause is usually age or corrosion, a main line leak sometimes signals the whole line is nearing the end of its life.
Written by the New Pro Plumbing content team and reviewed for technical accuracy by Miguel Lopez, owner and California-licensed plumber (CSLB #974600). Guidance follows U.S. EPA, CSLB, and LADBS sources where cited. Any figures reflect New Pro Plumbing's flat-rate practice and West LA conditions, not a quote — we confirm pricing in writing before any work begins.
Last reviewed: August 2026.
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