Underground & water line leak detection in Brisbane, CA
An underground water leak is pressurized drinking water escaping from a buried pipe, usually the private service line that runs from the meter to your building. Underground leak detection narrows down which buried section is losing water, and roughly where, before anyone breaks ground. Brisbane Leakmark takes inquiries about suspected buried supply-line leaks for properties in Brisbane and the nearby communities shown on our service areas page.
Before anyone digs, call. We’ll ask where the meter sits, where the wet ground is and what runs between them.
Call (415) 532-1415How is an underground water leak different from an indoor leak?
A buried supply line is normally pressurized, so a break can lose water even with fixtures off. Soil, gravel and paving can carry the water away before it surfaces, so the wet spot and the leak often aren’t in the same place.
Underground leak detection concerns pressurized water lines beneath soil or paving. Buried drains and sewer laterals carry wastewater at low pressure and need different testing. Irrigation lines carry pressurized water too, but they belong to a separate system with its own valves.
Which buried pipe could be leaking?
Distinguishing the pipe types helps describe the issue and decide which party to contact.
| Term | What it is | Typical location | Why it matters |
|---|---|---|---|
| Utility main | The public distribution pipe that serves many properties | Usually under or beside the street | Maintained by the water utility, not a private contractor |
| Meter and meter box | Where the utility measures your use | Often near the front of the lot | Do not adjust the meter or utility-side equipment; contact the utility if it appears damaged |
| Private service line | The pipe from the meter to the building | Under yard, driveway or path | The most common subject of underground leak detection |
| Branch pipe | A buried tee feeding a hose bib, outbuilding or second unit | Off the service line | Often missed, and can hold the actual leak |
| Irrigation branch | A pipe feeding sprinkler or drip valves | Garden areas, planter beds | Looks like a service-line leak on the meter |
Each property is different. Where the boundary between public and private pipe falls, and who owns it, has to be confirmed rather than assumed.
What outdoor signs may point to a buried water leak?
Look for these, especially during dry weather:
- A strip of lawn or soil that’s greener, softer or wetter than the rest
- Water seeping from a crack in the driveway, path or retaining wall
- A sunken or soft spot along the likely route from the meter to the building
- Constant dampness inside the meter box when nothing is running
- A hissing sound near the meter or where the pipe enters the building
Each is worth checking. None proves a buried supply leak on its own.
Why might the yard be wet without a pipe leak?
Before blaming the service line, rule out the usual alternatives.
| Possible cause | What points to it | What points away from it |
|---|---|---|
| Recent rain | Wet ground across a wide area that dries within days | Wetness that stays put in a single spot during dry spells |
| Runoff from a slope or neighbor | Water arrives after rain and follows the grade | Water appears with no rain and no upslope source |
| Downspout or yard drain | Wetness near drain outlets, mainly during storms | Meter keeps turning with everything off |
| Irrigation line or head | Wet near planters, worse after watering cycles | Wet spot nowhere near any irrigation and stays wet with it off |
| Sewer or drain lateral | Odor, wet area that worsens after flushing or showers | Clear water and a meter that moves |
| Buried supply leak | Meter moves with all water off, area stays wet | Meter is still with the house shut off |
Meter readings can help identify unexplained metered use, but they cannot tell whether the loss is at a buried supply line, an irrigation branch, a toilet or somewhere else.
Changes in usage or pressure
A higher bill or weaker pressure is a clue, not a diagnosis.
A rise in use
Tells you more water is passing through the meter. It doesn’t tell you whether that water went to a buried pipe, a running toilet or longer watering cycles.
A drop in pressure
Can come from a large service-line leak, a partly closed valve, a failing regulator or nearby utility work such as main flushing.
Our high water bill guide for Brisbane covers the billing side in more detail.
Who may be responsible near the water meter?
Use this sequence to decide who to call, not to settle who is legally responsible.
- Is water coming up in the street, gutter or public sidewalk? → Contact City of Brisbane Public Works at 415-508-2130.
- Is the meter itself, or the box around it, leaking or damaged? → Report it to Public Works. Don’t open, adjust or repair the meter.
- Is the wet area between the meter and your building? → This is usually where a private investigation starts. If unsure, ask Public Works first.
- Is the wet area near the building, an outbuilding or a garden? → Likely a private service line, branch or irrigation pipe.
Our city main vs private line guide explains the general concepts. For your address, the City’s answer is the one that counts.
What to photograph before calling
- The wet area from a distance and up close, with something for scale
- The meter dial and its leak indicator, with the time noted, if you can view it safely
- Where the pipe enters the building and the main shutoff valve
- Hose bibs, outbuildings and irrigation valve boxes near the wet area
- Paving, retaining walls or planters over the likely pipe route
Meter checks for a suspected buried supply leak
These steps confirm that water is being lost. They won’t show where.
- Shut off all water use indoors and outdoors, including irrigation at the controller.
- Read the meter if the lid lifts easily and safely. Note the full reading and the leak indicator.
- Wait 30–60 minutes with nothing running, then read it again.
- Close the building’s main shutoff if accessible and working, then watch the meter again.
- Interpret carefully: if the meter still moves with the building shut off, the loss is probably between the meter and that valve.
If a valve is stiff, corroded or leaking, stop. Forcing an old valve can break it. See how to check a water meter for leaks for the full routine.
How line isolation can narrow the search
Isolation divides the system into sections and tests them one at a time—the step that most often stops digging in the wrong place.
Meter still moves with the building main closed?
Yes → upstream of the building valve. Close irrigation next.
- Meter stops → investigate the irrigation system.
- Meter still moves → suspect the service line or a buried branch.
No → check building-side plumbing
Including fixtures, walls and any under-slab lines. The appropriate investigation depends on what other observations show.
This only works where valves exist and still function. Many older properties have fewer valves than this assumes.
Mapping probable buried pipe routes
The investigator first works out where the pipe likely runs, using the meter location, the building entry point, hose bibs and any plans. Metal pipe can often be traced electronically. Plastic is harder and may need a tracer method or careful inference. The result is a probable route, not a certainty, because pipes are sometimes rerouted without records.
Acoustic investigation on buried lines
Escaping pressurized water can make sound that listening equipment may pick up along the route. Results depend on conditions:
Pipe material
Metal pipe carries sound well. Plastic pipe dampens it.
Depth and soil
Deeper lines and loose or wet soil muffle sound.
Surface
Concrete, decking and thick planting change what can be heard.
Background noise
Traffic, wind, pumps and running water can mask the signal.
Ask which acoustic tools, if any, would be appropriate for the pipe and available for the appointment. Acoustic results support a conclusion. They’re rarely the only evidence for one.
When pressure testing can help
A pressure test isolates a pipe section and monitors it for pressure changes. A pressure drop may indicate leakage, but the test setup, temperature and valve behavior must also be considered.
Confirms which section fails
Such as the main service line versus a branch.
Doesn’t locate the leak point
Location still has to come from route mapping, listening and ground evidence.
How hardscape and landscaping affect access
What’s on top of the pipe shapes how a leak can be confirmed and reached.
| Surface over the line | Effect on investigation | Effect on access |
|---|---|---|
| Lawn or open soil | Wet signs are easier to see. Listening varies with soil | Simplest to open and restore |
| Concrete driveway or path | Water may surface away from the leak | Cutting and patching needed |
| Pavers or stone | May need lifting to confirm | Can often be lifted and reset |
| Decking | Blocks direct listening and viewing | Boards or framing may need removal |
| Mature planting or trees | Roots and mulch hide wet signs | Work around roots needs care |
| Retaining walls or steep grade | Water follows the slope | Structural and safety limits on digging |
Excavation may need permits depending on the location and scope. Before digging, use the 811 notification process and confirm that affected utility owners have responded.
Why a pinpoint estimate may be provisional
Confidence is higher when isolation, route mapping and listening agree, and lower when the mark rests on one weak signal. Some cases still require exposing the line to confirm the failure. Ask how confident the assessment is and what happens if an opening does not reveal the suspected failure.
What happens if no leak is found on the supply line?
- Irrigation: a valve or lateral leaking only when the system is pressurized
- Building plumbing: a slab, wall or fixture leak after the main shutoff
- Drainage: runoff, a downspout or a yard drain causing the wet ground
- Sewer lateral: wastewater leaking, which needs a different investigation
- Utility side: a problem at the meter or main, which goes to the City
When City Public Works is the right contact
- Water rises from the street, gutter or public sidewalk
- The meter, meter box or anything at the curb is leaking or damaged
- You need to confirm whether a pipe or area is public or private
City of Brisbane Public Works, 50 Park Place: 415-508-2130.
Excavation in the right-of-way needs an encroachment permit; grading above five cubic yards needs a separate permit. Before digging, contact 811 (two working days’ notice).
What comes after finding a buried leak
Repair is a separate job with its own decisions about access, materials, permits and surface restoration. Whether we can take on the dig and repair should be confirmed before scheduling. See underground water line repair for how that work is approached.
Repair versus replacement of a private line
After confirmation, the choice usually comes down to a few factors.
| Situation | Spot repair | Replacement / reroute |
|---|---|---|
| Single leak, rest of pipe in good shape | Yes | — |
| Several past leaks on the same line | — | Yes |
| Pipe visibly corroded or brittle when exposed | — | Yes |
| Leak under expensive hardscape | Yes | Yes |
| Short-term fix needed before a sale or remodel | Yes | — |
These are starting points, not quotes. The pipe’s condition once exposed often decides it.
Brisbane’s water-district context
For Brisbane property owners · City of Brisbane
- SFPUC is Brisbane’s sole wholesale water source. Your account, meter and billing sit with the City, not SFPUC.
- The City water distribution page identifies GVMID with Crocker Park and Northeast Ridge and the Brisbane Water District with Central Brisbane, Sierra Point and Baylands.
- The districts are interconnected, with 12 pressure-reducing valve stations.
- Routine flushing may temporarily lower pressure or discolor water at notified addresses.
For meter, billing or main questions, contact the City of Brisbane, not SFPUC.
Comparing underground leak investigation options
Questions worth asking any provider before booking:
- How will you isolate sections before recommending any digging?
- How do you trace plastic pipe versus metal pipe?
- What happens if the first opening doesn’t find the leak?
- Who arranges 811 marking and any City permits?
- Who will perform any separate repair work, and what does it include?
Underground leak FAQs
Is a wet patch always a broken underground water pipe?
No. Rain, drainage, irrigation and sewer problems can all make soil wet. A consistently wet area during dry weather combined with unexplained meter movement warrants investigating the pressurized supply system, but neither water clarity nor one meter reading proves the location.
How can I distinguish a private line from a city water main?
Mains generally run along the street and serve many properties. Your service line runs from your meter toward your building. Where the boundary falls on a particular lot isn’t published as one City rule. Call Brisbane Public Works at 415-508-2130 to confirm before any digging near the meter or street.
Can a moving meter point to an underground leak?
It can point toward one. If the meter keeps moving after you close the building’s main shutoff and turn off irrigation, the loss is likely between the meter and the building. It still does not establish where the water is being lost.
How are buried plastic pipes located?
Plastic pipes generally cannot be traced directly with the same electromagnetic methods used for conductive metal lines. Investigators may combine records, endpoints, tracer wires or other suitable locating methods.
Will workers need to dig to confirm the leak?
Often, yes, at the final stage. Testing can narrow the leak to a likely spot, but seeing the pipe is the only full confirmation. Excavation requires the appropriate 811 notice and utility responses, and work in the City’s right-of-way or easements may require an encroachment permit.
Can irrigation leaks look like a service-line failure?
Yes. Irrigation pipes are pressurized and often branch off near the service line, so both can make the meter move and wet the soil. Closing the irrigation supply and rechecking the meter usually separates them.
Does finding the leak include fixing the line?
Not automatically. Detection ends with a located leak and the findings explained. Repair is separate work involving access, materials, permits and surface restoration. Whether Brisbane Leakmark can carry out the repair should be confirmed before scheduling. Ask about this on your first call.
What if water surfaces in a public street?
Report it to City of Brisbane Public Works at 415-508-2130. Water in a street or gutter may involve City infrastructure; Public Works should assess it before a private provider assumes responsibility.
Call about a possible buried leak
A meter that won’t stop and ground that won’t dry are worth checking before anyone digs. Describe the yard, the meter and the wet spot, and we’ll suggest where an investigation should start.
Call (415) 532-1415