Main Water Line Leak: Signs, Repair Costs & Who to Call (2026)

The Leak You Can't See: Your Main Water Line

The pipe between the street meter and your house carries pressurized water 24/7, buried where you'll never see it fail. It announces failure indirectly — through the meter, the bill, the yard, or the basement wall — and nearly 900 people a month search for what to do about it. Here is the confirmation test, the real costs, and the responsibility line that decides who pays.

The Five Signs

1. 1The meter moves with everything off — the definitive sign; the test below confirms it in 20 minutes.
2. 2A bill jump of 30%+ with no usage change — a modest 1/8-inch leak wastes thousands of gallons a month.
3. 3A wet, soft, or suspiciously lush strip in the yard tracing the line between meter and house — the lawn drinks the evidence.
4. 4Hissing near the meter box or where the line enters the house.
5. 5Whole-house low pressure — pressure lost to the soil before it reaches your fixtures.

Water arriving in the basement near the entry point deserves its own attention — water coming up through the basement floor covers separating a supply leak from groundwater, which look alike and get fixed very differently.

The 20-Minute Meter Test

Shut every fixture and water-using appliance (irrigation and ice maker included), photograph the meter — especially the low-flow indicator, the small triangle that spins at any flow — wait 20–30 minutes touching nothing, and look again. Movement with the house at zero draw is a leak on your side of the meter, full stop.

Then the isolating step most people skip: shut the house-side main valve and watch again. Still moving → the leak is in the buried line (the underground repair). Stopped → the leak is *inside* the house, which is a cheaper hunt and a different guide. This one valve-turn is the difference between calling the right trade and paying for exploratory digging.

What the Repair Costs

Three cost drivers: length and depth of the run, what sits above it (grass is cheap, driveways and tree roots aren't), and pipe material — a failing polybutylene or 60-year-old galvanized line should be replaced, not patched, because the next failure is already scheduled. Ask specifically about trenchless options: pulling a new line through the old one's path skips the excavation-and-restore cycle that dominates open-trench quotes.

Whose Pipe Is It?

The near-universal US rule: the utility owns up to the meter; you own meter-to-house. Confirm with one call to your utility — and while on that call, ask whether the leak might be on their side (pre-meter leaks are their repair, free to you).

The insurance picture has the same split: standard homeowners policies typically cover the damage the water causes to your home but not the buried pipe repair — the gap that service-line riders ($20–$50/year) exist to fill. If your policy lacks one, add it after this repair, not before the next. Either way, document everything before repairs begin: the bill spike, the meter photos, the wet yard, and any indoor damage.

Who to Call

A licensed plumber who does service-line and underground work — ask directly, because not every plumber digs, and the ones who don't will happily bill a visit to tell you so. For active water in the basement, the pipe repair and the indoor water are two scopes: shut the main (a $12 meter key opens the curb box if your inside valve fails), and treat the wet basement as its own restoration decision — drying subfloor and framing to verified numbers is what keeps a plumbing bill from growing a mold addendum. What that restoration side costs is worth knowing before the plumber's backhoe becomes the day's only focus.

Bottom Line

Confirm with the meter test, isolate with the house valve, get two quotes from underground-capable plumbers (one must price trenchless), check the utility side and your rider situation before paying — and if the basement got wet along the way, dry it like it matters, because it does.