Underground Leak Detection in Redwood City
A bill that jumped for no clear reason, a soggy patch that never dries, or a strip of grass greener than the rest of the yard — these are the classic signs of a buried problem. Our Underground Leak Detection in Redwood City traces the line from the meter to the house, finds whether the loss is on the pressure side or the drain side, and marks the spot before any digging starts. You get a written report of what failed and where, so the repair — and any conversation with the City about the bill — starts from documented facts.
Why a Buried Yard Leak Hides So Well
It hides because the water never has to surface where you can see it, and saturated soil can carry it away from the break for a long time.
The line from the meter to the house runs under soil, driveway, and lawn. When it breaks, water can drain downward or sideways through the ground instead of pooling on the surface, so the first signs are usually indirect: a bill that jumps with no change in use, pressure that fades across the house, a soggy patch that never dries, or a strip of grass greener than everything around it.
Redwood City's housing stock makes this a common story. The City's Housing Element notes that 61% of homes here were built between 1940 and 1980, so many service lines have been in the ground for decades. The city's Hetch Hetchy supply is very soft water, about 8 mg/L hardness, so mineral buildup is not the usual suspect here — age, pressure, and soil movement around a buried line are the factors that matter most.
- A soggy patch that stays wet through dry weather
- Greener, faster-growing grass in a line across the yard
- A water bill that jumps with no leak visible indoors
- Low pressure at every fixture at once
- The sound of running water when everything is off
- Pooling near the meter box or along the driveway
The Meter-to-House Run
The service line is the single pipe that carries water from the street meter into your home. A break anywhere along it behaves the same way at first: lost water, a moving meter, and no wet spot inside. That is why the search starts at the meter and works toward the house, narrowing the run section by section instead of digging at the first damp spot.
Serving ZIPs 94061 through 94065, open 24 hours, 7 days a week. Call (650) 632-9185 or visit our contact page.
Pressure Side or Drain Side? The First Split That Matters
This split decides the whole search: a pressure-side leak runs constantly, while a drain-side leak only flows when a fixture drains.
Pressure-Side Signs
A supply leak never sleeps. The meter moves with everything off, the bill climbs steadily, and the yard may stay damp in one line-shaped area. These are the leaks that surprise homeowners with thousands of extra gallons in a month.
Drain-Side Signs
A drain leak only appears when water runs through it — after a shower, a laundry load, or a dishwasher cycle. The meter test comes back clean, but soil near a drain run stays wet and the dampness follows fixture use.
Why the Split Saves Money
Testing the two sides separately keeps the crew from chasing the wrong system. Acoustic listening and pressure testing suit a pressurized line; a drain-side problem is traced by running fixtures one at a time and watching where moisture appears.
How the Meter Test Confirms a Buried Leak
The meter test is the fastest truth test: with everything off, a moving meter proves water is leaving the system somewhere.
Start by turning off every tap, toilet fill, appliance, and irrigation zone, then read the meter's low-flow indicator. If it moves, there is a leak. Shut the main valve at the house and read it again: a meter that stops points inside the house, while a meter that keeps moving points to the buried line between the meter and the house.
Redwood City homeowners have a second check that costs nothing. The City's My Water portal shows hourly usage from the smart meter, so you can see exactly when the loss happens — a steady overnight trickle looks very different from a daytime irrigation spike — and usage alerts can catch the next jump early. Bring that hourly picture to the visit; it narrows the search before any equipment comes out.
Fixtures Off, Meter Read
Everything water-using goes off, then the low-flow indicator is watched for movement over several minutes.
House Valve Shut
Closing the house valve splits the system in two and shows whether the loss is indoors or on the buried run.
Acoustic Tracing
Listening equipment follows the buried line and peaks over the break, marking the spot from above ground.
Pressure Check
A pressure reading confirms the loss rate and can reveal a failing pressure regulator, which sometimes mimics a leak.
What Your Service Line Is Made Of, and How to Tell
A quick look at the pipe where it enters the house usually identifies the material, and the material shapes how the line fails.
Galvanized steel shows as dull gray, is magnetic, and typically has threaded joints — it was common in the pre-1960s era and corrodes from the inside over decades. Copper shows brown or reddish with a green tarnish where it has aged. Plastic lines are usually black, white, or blue. Each material fails differently, so naming it is part of the diagnosis, not trivia.
One question comes up often enough to answer plainly: the City's 2021 through October 2025 inspection of the customer-side service lines found no lead. If your line's material is still a mystery, the entry-point check during a detection visit identifies it without excavation.
Note that California plumbing work on jobs of $1,000 or more combined labor and materials requires a CSLB C-36 plumbing contractor license as a general rule. Detection visits are quoted separately from repair work, so you can see both numbers before deciding anything.
What Buried-Line Locating Costs
Locating is priced as its own job, in ranges, before any repair is discussed.
| Service | Typical Range |
|---|---|
| Leak detection visit | $150 – $600 |
| Slab and underground locating | $500 – $1,200 |
Detection is always quoted separately from the repair. Once the break is marked, you get the repair options in ranges as well — a section repair or a reroute of the buried run — and you choose before any digging starts. The ranges above match what we publish across our leak detection services in Redwood City.
Related Leak Services
Buried-line problems often travel with other aging-pipe problems, so these are the services homeowners pair with this one most often.
Slab Leak Detection
For slab and Eichler homes in town — leaks under concrete, pinpointed electronically before any concrete is opened.
Slab leak detection in Redwood City →Water Leak Detection
Hidden leaks in walls, ceilings and buried yard lines, traced without tearing the house apart.
More on our water leak detection service →Irrigation Leak Repair
When the soggy patch turns out to be a sprinkler or irrigation line rather than the main service line.
Irrigation leak help →Buried-Line Questions Homeowners Ask Us
The questions below cover the meter test, yard signs, pipe materials, and cost — the things homeowners ask before booking a visit.
How do I check my meter to confirm a buried leak before I call?
Turn off every fixture and appliance that uses water, then watch the meter's low-flow indicator. If it still moves, water is leaving the system somewhere. Shutting the house valve and watching again is the next split: if the meter stops, the loss is inside the house; if it keeps moving, the loss is on the line between the meter and the house.
My yard is soggy in one spot. Is that always a service-line leak?
Not always. A soggy patch can come from a sprinkler head, a drain line, or poor drainage after rain. The pattern that points to a buried supply leak is a patch that stays wet through dry weather, sits along the path from the meter to the house, and comes with a rising bill or a drop in pressure.
Why is one strip of grass greener than the rest of the lawn?
A steady underground leak feeds one area constantly, so the grass above it grows faster and stays greener while the rest of the lawn follows normal watering. It is one of the most reliable visible clues for a yard-line leak, especially when the green strip runs in a line rather than a round patch.
What is the difference between a pressure-side leak and a drain-side leak?
A pressure-side leak is on a supply line that stays pressurized all day, so it leaks continuously and drives the bill up around the clock. A drain-side leak only flows when a fixture drains, so it appears in bursts and usually shows up as wet soil near a drain run rather than a constant loss at the meter.
Can a buried leak cause low water pressure through the whole house?
Yes. A supply line losing water underground delivers less pressure and flow to every fixture, so showers weaken and taps run slowly at the same time. Low pressure in one fixture usually points to that fixture; low pressure everywhere, paired with a high bill, points to the line feeding the house.
How do I tell galvanized pipe from copper on my service line?
Galvanized pipe looks dull gray, feels magnetic, and usually has threaded joints. Copper looks brown or reddish and often carries a green tarnish where it has aged. Plastic service lines are usually black, white, or blue. Identifying the material helps judge how the line is likely failing and what a lasting fix looks like.
Did the City find lead service lines in Redwood City?
The City's 2021 through October 2025 inspection of the customer-side service lines found no lead. If you are unsure what your own line is made of, a visual material check during a detection visit settles it without digging.
How much does buried-line locating cost, and will you have to dig up my yard?
Detection visits typically run $150 to $600, and slab and underground locating typically runs $500 to $1,200. Detection is quoted separately from any repair. Locating comes first and the spot is marked, so any digging that follows is limited to the marked area rather than a trench across the yard.
Think the Leak Is Between the Meter and the House? Get It Confirmed.
A buried supply leak runs around the clock and the bill keeps climbing while it does. One visit tells you which side is losing water, where the break is, and what the repair will cost — in ranges, in writing, before you commit to anything.
Call (650) 632-9185 Request a Quote