Before we arrive
Note when you first noticed the bill or the warm spot, run the meter test if you can, and clear access to the meter, the main shutoff and the water heater.
Costa Mesa plumbing service
Leak detection and slab leak repair in Costa Mesa
A water bill that jumped, a warm spot on the floor, or the sound of running water when nothing is on? We find the leak with meter tests, acoustic listening and thermal imaging before anyone opens a floor.
Call (657) 669-4766Request service
Written and fact-checked by John, editor, MBA in marketing
Updated against City, utility and state sources
Quick answer
To check for a hidden leak, turn off every fixture and read your water meter, then read it again after two hours with no water used, as EPA WaterSense suggests. If it moved, you likely have a leak. In 1960s and 1970s Costa Mesa slab homes, a common cause is a water line under the concrete. Call (657) 669-4766 for detection.
- Homes built 1960 to 1979
- About 49.5% (City data)
- Household leaks
- 9,300+ gallons a year (EPA)
- Mesa Water rate
- $6.38 per 748-gallon unit (2026)
Signs of a hidden or slab leak
The most common signs of a hidden leak are a water bill that rises with no change in use, a meter that moves when nothing is running, and warm or damp spots on a floor.
Leaks inside walls and under concrete stay hidden for a long time. By the time water shows on the surface, it may have been running for weeks. These are the signs we hear about most often on calls:
- A higher water bill with no new landscaping, guests or pool fill
- The water meter dial or leak indicator turning with every fixture off
- A warm patch on a tile or concrete floor, often in a hallway, kitchen or bathroom
- The sound of water running in a wall or under the floor at night
- Damp or lifting carpet, swelling baseboards or cupped wood flooring
- New cracks in a floor or wall, or mildew smell with no visible source
- A water heater that runs more than usual, a sign of a hot water line leak
- Low water pressure at several fixtures
Why slab leaks are common in Costa Mesa's 1960s and 1970s homes
About half of Costa Mesa's homes were built in the 1960s and 1970s, and many of them sit on concrete slabs with water lines running underneath that are now more than 45 years old.
The City's 2021 Housing Element, using Census survey data, shows 25.4% of Costa Mesa homes were built in the 1960s and 24.1% in the 1970s. Add the 19.2% built in the 1950s and the 4.2% before that, and about 73% of the city's homes predate 1980. Neighborhoods such as Mesa Verde, built mostly in the 1960s and 1970s, are full of single-story slab homes from this era.
In a slab home, the water lines often run under or through the concrete to reach the kitchen and bathrooms. Over decades, those lines can fail for several reasons:
- Pipe wear from water flow and age, which thins the pipe wall over time, faster at bends and fittings.
- Abrasion where the pipe touches concrete, gravel or another pipe, as the line expands and contracts with every hot water draw.
- Movement in the slab and soil, which can stress a buried line.
- Hot water lines in particular, since heating and cooling cycles put more stress on the pipe.
A single slab leak is often a repair. A second or third leak in a few years, or pinhole leaks showing up elsewhere in the house, suggests the whole system is wearing out. That is when a repipe enters the conversation, and our whole-house repiping page covers PEX and copper repipes for homes from the 1950s to 1970s.
How to do the EPA water meter leak test
EPA WaterSense says to check your water meter before and after a two-hour period when no water is being used; if the reading changes at all, you probably have a leak.
Find the meter
In Costa Mesa it is usually in a box near the curb or sidewalk in front of the home. Lift the lid carefully; spiders and standing water are common. Your water comes from Mesa Water District or the Irvine Ranch Water District (IRWD); do not force the meter, its lid lock or its valve.
Stop all water use
Turn off faucets, the dishwasher, washer, ice maker and irrigation. Make sure no toilet is refilling. Pick a time when no one will use water for two hours.
Read and record
Write down the full reading, or take a photo. Many meters also have a small triangle or dial that spins with even a tiny flow.
Wait two hours, then read again
If the number changed or the leak indicator moved, water is going somewhere. That is the point to call a plumber for detection.
Narrow it down
Close the main shutoff at the house and watch the meter. If it still moves, the leak may be on the line between the meter and the house. If it stops, the leak is inside the home's plumbing.
Toilets are the most common indoor leak and the easiest to check. Put a few drops of food coloring in the tank, wait 10 to 15 minutes without flushing, and look for color in the bowl. If it shows up, the flapper is leaking. Our toilet and faucet repair page covers that fix.
Why the meter test fails in apartments with a shared meter
The meter test only works when one meter serves one home; in a building where several units share one meter, someone else's water use moves the dial and hides or fakes a leak.
This matters in Costa Mesa. The City's 2023 economic profile counts about 44,239 housing units, with 35.4% in buildings of five or more units and only 40.3% owner-occupied. Many apartment buildings are served by one meter for several units or the whole property. When a tenant in one unit runs the test, the neighbors' showers, dishwashers and toilets keep the meter turning.
What a tenant can check instead
- Do the toilet dye test on every toilet in the unit.
- Listen for running water at night with everything off.
- Feel floors for warm spots and check under sinks and around the water heater, if your unit has one.
- Report what you find to your landlord or property manager in writing. In a shared-meter building the tenant often never sees the water bill, so the owner may not know.
What owners and managers can do
- Run the meter test during a quiet period, with tenants told not to use water for the test window.
- Compare bills month over month. A jump with no change in occupancy points to a leak somewhere on the property.
- Have a plumber isolate sections of the building with valves, if the building has them, and watch the meter as each section is closed.
- Pressure test individual units' lines where the system allows it.
Our landlord and property manager page covers leak detection across multi-unit buildings, including tenant notice and access.
How we find hidden leaks: acoustic, thermal and pressure testing
Leak detection combines pressure testing to confirm which line is leaking, acoustic listening to hear where the water escapes, and thermal imaging to see the temperature pattern that leaking water leaves behind.
| Method | How it works | Best for |
|---|---|---|
| Meter and pressure test | Shut off fixtures and watch the meter or a gauge; isolate hot and cold lines to see which loses pressure | Confirming there is a leak and which line it is on |
| Acoustic detection | Sensitive ground microphones and headphones pick up the hiss of water escaping a pressurized pipe through concrete or walls | Pinpointing a leak under a slab or behind finished walls |
| Thermal imaging | An infrared camera shows warm or cool patterns on floors and walls; a hot water leak spreads heat through the slab | Hot water slab leaks, tracing pipe routes |
| Line tracing | An electronic locator follows the path of a metal pipe under the floor | Mapping where buried lines run before listening |
| Moisture meter | Measures moisture in drywall, wood and flooring | Finding the edges of a wet area in walls and floors |
No single tool is perfect. Acoustic detection works best when the house is quiet, so we may ask you to turn off fans, the refrigerator ice maker and irrigation during the test. Thermal imaging works best on hot water leaks because the warm water shows up against a cooler slab. A cold water leak in a slab is harder to see and leans more on acoustic listening and pressure testing.
The goal is to mark the leak closely enough that any repair opens the smallest possible area. You get a written summary of what was tested, what was found and where the leak is marked.
Slab leak repair options
Once the leak is found, the three main repairs are a spot repair through the slab, a reroute that abandons the buried line and runs a new one above the floor, or a repipe of the whole house.
| Option | What happens | Good fit when | Tradeoffs |
|---|---|---|---|
| Spot repair through the slab | Open the floor at the marked spot, repair the pipe, patch the concrete | First leak, pipe otherwise sound, easy floor to open | Flooring has to be removed and replaced; the rest of the old pipe stays |
| Reroute the line | Leave the leaking line in the slab and run a new line through walls, attic or ceiling | Leak under hard-to-replace flooring or a cabinet, line likely to leak again | Drywall openings to patch; route has to fit the house |
| Whole-house repipe | Replace the home's water lines, usually above the slab, with PEX or copper | Repeat leaks, pinholes elsewhere, old pipe throughout | Larger project; solves the system, not just one leak |
The right choice depends on the pipe's condition, where the leak is and what sits on top of it. A leak under a tiled kitchen is a different decision from one under a garage floor. We price each workable option in writing so you can compare. When the work changes or replaces water lines, the City of Costa Mesa plumbing permit application includes Water Repipe as a work type, and we pull the permit when the job requires one. Our Costa Mesa plumbing permit guide explains the City process.
About insurance
Many homeowners policies treat the cost of finding a leak and repairing the damage differently from the cost of fixing the pipe. Coverage varies by policy. Call your insurer before major work starts, and keep our written detection summary and photos for the claim.
What a leak does to your Mesa Water bill
Mesa Water District bills water by the unit, and in 2026 the potable water rate is $6.38 per unit, with one unit equal to 100 cubic feet or 748 gallons.
EPA WaterSense says the average household's leaks can account for more than 9,300 gallons of water wasted every year. At 748 gallons per unit, that is more than 12 billing units of water a year that never reached a faucet. A slab leak on a hot water line can waste far more, and it also makes the water heater run to keep reheating the water that leaks away.
Reading your bill
- Find the units used for each billing period on your Mesa Water bill and compare them to the same period last year.
- A rise with no new irrigation, pool fill or extra people at home is worth a meter test.
- If your bill comes from IRWD instead, the same test applies. IRWD serves parts of Costa Mesa; your bill shows which district serves you.
Which side of the meter is yours to fix
Mesa Water completed its first service line inventory in 2024 and reported no lead or galvanized service lines requiring replacement in its distribution system. If you see water bubbling up near the meter box or in the street, call Mesa Water at 949-631-1200. After hours, press 9 for Costa Mesa Police or call 714-754-5251. IRWD customers can call 949-453-5300. Leaks on the house side of the meter are a plumber's job. Our who to call for water and sewer guide sorts out the agencies.
Leak detection and slab leak repair cost in Costa Mesa
HomeAdvisor data published by Angi puts slab leak detection at $150 to $600 and slab leak repair at $630 to $4,400 (2024), with a whole-house repipe published at $1,500 to $15,000.
| Job | Published range | Source and year |
|---|---|---|
| Slab leak detection | $150 to $600 | HomeAdvisor via Angi, 2024 (national) |
| Slab leak repair | $630 to $4,400 | HomeAdvisor via Angi, 2024 (national) |
| Whole-house repipe | $1,500 to $15,000 | Angi (national) |
| Typical plumbing job in Costa Mesa | $117 to $391 | This Old House, Costa Mesa page |
These are published estimates, not our prices. What moves the price:
- How many tests it takes to pinpoint the leak
- Whether the leak is under tile, hardwood, carpet or a bare garage slab
- Spot repair versus reroute versus repipe
- Drywall and flooring repair after the plumbing work
- Permits, when the job requires one
You get the price in writing before work starts. Call (657) 669-4766 for an exact quote. For more ranges, see our Costa Mesa plumbing cost guide.
What happens on a leak detection visit
A leak detection visit confirms the leak, identifies the line, pinpoints the spot and ends with written repair options, all before any floor or wall is opened.
Confirm and isolate
The plumber checks the meter, then isolates hot and cold lines to see which one is losing pressure. That narrows the search to one system.
Trace and listen
The line route is traced, then acoustic and thermal tools pinpoint the leak. The spot is marked on the floor or wall.
Written options
You get a summary of findings and a written price for each repair that fits. Work is performed by independent CSLB-licensed C-36 contractors; see our license check guide.
We find leaks across Costa Mesa, from the slab homes of Mesa Verde to the apartments and houses of the Westside and the mixed-age homes of the Eastside. If a leaking water heater turns out to be the source, our water heater repair page takes it from there.
Water where it shouldn't be? Call now.
A real person answers 24 hours a day. You get an honest arrival window and a written price before any work starts.
Questions Costa Mesa homeowners ask
How do I know if I have a slab leak?
Common signs are a warm spot on the floor, the sound of running water with everything off, a water meter that moves when nothing is on, and a bill that rises for no clear reason. In Costa Mesa's 1960s and 1970s slab homes, buried water lines are a frequent source. Call (657) 669-4766 for detection.
How do I check my water meter for a leak?
Turn off all water use, read the meter, wait two hours without using any water, and read it again. EPA WaterSense says that if the reading changed at all, you probably have a leak. Then close the house shutoff to see whether the leak is inside the home or on the line from the meter.
Why doesn't the meter test work in my apartment?
If several units share one meter, your neighbors' water use keeps the meter moving, so the test cannot isolate your unit. Do a toilet dye test, listen for running water at night, check for warm floors, and report findings to your landlord or property manager in writing.
How much does slab leak detection cost in Costa Mesa?
HomeAdvisor data published by Angi gives a national range of $150 to $600 for slab leak detection and $630 to $4,400 for slab leak repair (2024). Those are estimates, not quotes. Flooring and repair method change the price. Call (657) 669-4766 for an exact quote in writing.
Should I repair a slab leak or repipe the house?
A first leak in otherwise sound pipe is often a spot repair or a reroute. Repeat leaks or pinholes elsewhere in the house usually mean the system is wearing out, and a repipe solves the problem instead of one leak. We price each option in writing. See our repiping page.
How much water does a leak waste?
EPA WaterSense says the average household's leaks can waste more than 9,300 gallons a year. Mesa Water bills by the unit, and one unit is 748 gallons, so that is more than 12 units a year. A hot water slab leak can waste more and also makes the water heater work harder.
Can you find a leak without breaking the floor?
Yes. Pressure testing, acoustic listening, line tracing and thermal imaging pinpoint most leaks before anything is opened. The floor or wall is only opened at the marked spot for a spot repair, and a reroute can avoid opening the floor at all.
Who do I call for a leak near the water meter?
If water is coming up near the meter box or in the street, call your water district first. Mesa Water is 949-631-1200, or after hours press 9 for Costa Mesa Police or call 714-754-5251. IRWD is 949-453-5300. Leaks on the house side of the meter are a plumber's job.
Sources
Facts on this page come from these public sources, checked November 1, 2026.
- EPA WaterSense, Fix a Leak Week
- Mesa Water District 2026 rates and fees
- Mesa Water District 2026 Consumer Confidence Report (2025 data)
- Mesa Water District, contact us
- IRWD 2026 report
- City of Costa Mesa Housing Element, April 2021 (year built data)
- City of Costa Mesa 2023 economic profile
- City of Costa Mesa plumbing permit application
- Mesa Verde (Costa Mesa), Wikipedia
- Angi (HomeAdvisor data), slab leak repair cost
- Angi, cost to repipe a house
- This Old House, Costa Mesa plumbing costs
- CSLB: Check a License