Underground Water Line Leak Detection
An underground water line leak is a break in the buried pipe between your meter and your home. Pros confirm it with a meter test and pressure checks, then locate it using acoustic listening and soil probes — without digging up the whole yard. FlowFast connects you with an independent local plumber who can find the leak and explain repair options.
- Connected with an independent local pro — never a call center queue.
- Part of our Leak Detection & Repair services — explained up front.
Parent service
Leak Detection & RepairHigh water bill or mystery damp spot? How pros find hidden leaks with acoustic and thermal tools, and how to get connected with an independent local plumber.
View all Leak Repair servicesThe main water line runs underground from the street meter to your house, and when it fails, the signs show up in the yard or on the bill. Look for an unusually green or soggy patch of lawn, soil that stays soft underfoot, water pooling where it never did before, or a bill that jumps while your usage stays the same. In winter-prone areas, freeze-thaw cycles can shift soil and stress the pipe; in older homes, corrosion simply wins over time. Because the pipe is buried, the leak can run for weeks before anyone notices.
Detection starts at the meter: with all water off in the house, a spinning meter proves water is escaping somewhere between the meter and the home. The plumber then pressure-tests the line and uses acoustic equipment to hear the leak through the soil, sometimes confirming with a probe rod. Marking the exact spot matters because it decides whether the fix is a small excavation or a full line replacement. FlowFast Plumbing is a referral service — we connect you with an independent local plumber for the detection visit.
Warning signs
Signs you need this service
- A section of lawn that stays soggy, sunken, or greener than the rest, even days after rain — water is feeding it from below.
- A water bill that rises sharply without any change in household use, suggesting water is escaping the buried line continuously.
- Noticeably lower water pressure at every fixture in the house, especially if it crept in gradually with no recent plumbing work done.
- The sound of running water near the meter or along the line's path when everything inside is off, or soil that feels soft underfoot.
What to expect
The process, step by step
The pro runs a meter test with all indoor water off — a moving meter confirms a leak between the meter and the house.
The line is pressure-tested to confirm the failure and rule out indoor plumbing as the source of the lost water.
Acoustic listening equipment scans the ground along the line's path, homing in on the vibration of water escaping under pressure.
The leak's location is marked with flags or paint, and you get a clear explanation of repair options before any digging.
Prevention
How to avoid this problem
- Know where your main shutoff and meter are, so you can stop water fast and run a meter check yourself.
- Before any yard digging project, call 811 to have utilities marked — striking the water line creates exactly this kind of leak.
- If your line is aging galvanized or polybutylene, periodic pressure checks catch weakening before a full underground break.
Frequently asked questions
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