Warm spot on the floor
A hot water line leaking under the slab can warm tile or flooring above it. Pets sometimes find these spots first.
Fountain Valley plumbing service
Leak detection and slab leak repair in Fountain Valley
Water meter spinning with everything off, a warm spot on the floor, or a bill that jumped for no reason? We find hidden and under-slab leaks with acoustic and thermal tools first, so nobody breaks a floor on a guess.
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, read your water meter, use no water for two hours, and read it again; the EPA says any change likely means a leak. In Fountain Valley's 1960s and 1970s slab homes, copper supply lines often run in or under the slab. A plumber locates the leak with acoustic and thermal tools, then you choose spot repair, reroute or repipe. Call (657) 669-4766.
- EPA meter test
- Two hours, no water use
- Household leaks
- 9,300+ gallons a year (EPA)
- Slab leak detection
- $150 to $600 (Angi 2024)
- City water hardness
- About 13 gpg (2025)
Signs of a hidden or slab leak
The most reliable sign of a hidden leak is a water meter that moves when nothing in the house is using water.
Most leaks we find in Fountain Valley are not dramatic. Water escapes slowly into a wall, under a cabinet or into the soil under a concrete slab, and the first clue is a number on a bill. The signs below do not prove a slab leak on their own, but two or more together are worth a call.
Sound of running water
A hiss or trickle you can hear with every fixture off, often clearest late at night when the house is quiet.
Water bill jump
A higher bill with no change in habits. Compare the same month last year to rule out seasonal irrigation.
Damp carpet or lifting floors
Wet carpet pad, cupping wood floors, or loose tiles away from any bathroom or kitchen.
Water heater always running
A tank that fires constantly can mean hot water is leaking out somewhere and the heater keeps refilling.
Low pressure
Pressure that drops at several fixtures. The City's water FAQ also lists a partly closed main valve, a clogged regulator screen and dirty aerators as causes, so check those too.
How to check for a leak with your water meter
The U.S. EPA's WaterSense program says to check your water meter before and after a two-hour period when no water is being used; if the meter changes at all, you probably have a leak.
Turn off every water use
Faucets, toilets, the washer, the dishwasher, the ice maker and the irrigation timer. Ask everyone in the house to wait two hours.
Find the meter
City water meters are usually in a concrete box near the curb or sidewalk in front of the home. Lift the lid carefully; spiders and standing water are common.
Write down the reading
Take a photo of the dial. Many meters also have a small leak indicator, a triangle or wheel that spins with even a tiny flow.
Wait two hours and read again
If the reading changed or the leak indicator moved, water is leaving the system somewhere.
Narrow it down
Close the house shutoff valve and watch the meter. If it still moves, the leak is between the meter and the house, or in irrigation. If it stops, the leak is inside the house or under the slab.
The EPA's numbers explain why this test matters. Its WaterSense program says the average household's leaks can waste more than 9,300 gallons a year, and nine percent of homes have leaks wasting 50 gallons or more a day. A toilet flapper that leaks silently will also move the meter, so check toilets before assuming a slab leak. Our toilet and faucet repair page covers running toilets.
Why slab leaks are common in 1960s and 1970s Fountain Valley homes
Most Fountain Valley homes were built during the 1960s and 1970s build-out, and copper supply lines in or under the concrete slab were typical for Orange County slab homes of that era.
The City's history describes the fast growth of the 1960s, built out under a master plan. The ranch homes of Central Fountain Valley around Brookhurst St and Warner Ave are typically from the 1960s and 1970s, and North Fountain Valley has established tracts where older homes often need updates. On a slab home of that age, the original hot and cold lines often run under or through the concrete to reach bathrooms and the kitchen. We treat that as typical for the era, not a fact about your house, until we test it.
Pipe under a slab lives a hard life. It sits against concrete and soil, it expands and contracts every time hot water runs, and it can rub where it passes through the slab or against rebar and gravel. After 50 or more years, small wear points become pinholes. Hot water lines tend to fail first because they move the most with temperature changes.
- Hot side leaks often show up as warm floors and a water heater that runs too much.
- Cold side leaks are quieter and often found only by the meter test.
- Leaks near the slab edge may show up as damp soil or a wet spot along the foundation outside.
The area's history adds context. The City notes the land was once known as the "Gospel Swamps", inundated by swamps and drained with canals before it could be farmed. A slab leak puts water into the soil under your home, which is one reason we do not recommend waiting on a known leak.
Hard water and pinhole leaks in copper
Fountain Valley's water is hard, averaging about 13 grains per gallon in 2025, and water chemistry is one of several factors that can contribute to pinhole leaks in copper pipe.
The City's 2026 Consumer Confidence Report puts 2025 total hardness at an average of 217 parts per million, or about 13 grains per gallon, with a range of roughly 10 to 15. In 2025 the City's supply was all groundwater from the Orange County Groundwater Basin, managed by the Orange County Water District, drawn from the City's wells. The City's FAQ notes that its well water is hard.
Pinhole leaks in copper have more than one cause. Water chemistry, high water velocity, poor original workmanship, stray electrical current and pipe age can all play a part, and more than one is often at work. We do not blame every pinhole on hardness. What we can say is that a house with one pinhole in old copper often has more on the way, because the same pipe, the same water and the same age apply everywhere in the system.
- One pinhole in 50 years: usually a spot repair.
- Second or third pinhole in a few years: time to price a reroute or a whole-house repipe.
- Green or blue stains at fittings: a sign of corrosion worth watching.
Hardness also shortens the life of water heaters and fixtures. Our water hardness guide explains the City's numbers in plain terms.
How we find a leak without breaking floors
Leak detection narrows the search with pressure tests, then pinpoints the leak with acoustic listening and thermal imaging, so any opening in a floor or wall is small and in the right place.
| Method | How it works | Best for |
|---|---|---|
| Meter and pressure test | Isolate hot and cold sides and watch for pressure loss on a gauge | Confirming a leak and which side it is on |
| Acoustic listening | Ground microphones and headphones pick up the sound of water escaping under pressure | Pinpointing leaks under slabs and in walls |
| Thermal imaging | An infrared camera shows warm or cool patterns on the floor or wall surface | Hot water leaks under tile, wood and drywall |
| Line tracing | An electronic locator maps where the pipe runs under the slab | Knowing the pipe path before listening or opening |
| Moisture meter | Reads moisture in drywall, baseboards and subfloor | Leaks in walls and cabinets, and damage mapping |
| Camera inspection | A small camera in a drain line | Drain leaks, which do not show on a pressure test |
Supply leaks are under constant pressure, so they make noise and lose pressure on a gauge. Drain leaks are not under pressure. A cracked drain under the slab only leaks when water runs, so it needs a different approach, usually a camera. If the camera finds a broken drain or sewer pipe, that becomes sewer line repair.
What happens on a leak detection visit
A leak detection visit confirms the leak, finds which line it is on, pinpoints the spot, and ends with written repair options.
Confirm there is a leak
We check the meter and fixtures, including toilets and the water heater relief valve, to rule out the simple causes.
Isolate hot, cold and irrigation
Pressure tests on each side tell us which line is leaking and whether it is inside or outside the house.
Trace the pipe
We map the route of the leaking line under the slab so the search area is small.
Pinpoint the leak
Acoustic listening and thermal imaging locate the spot. We mark it on the floor.
Written report and options
You get what we found, where, and written prices for each repair option. Photos and readings go in the report for your insurer.
Slab leak repair: spot repair, reroute or repipe
A single leak in otherwise good pipe is usually a spot repair, a line with several leaks is usually rerouted overhead, and a house with leaks on many lines is usually a candidate for a repipe.
| Option | What it involves | When it fits | Published estimate |
|---|---|---|---|
| Spot repair through the slab | Open the floor and slab over the leak, repair the pipe, patch the concrete and floor | First leak, pipe in fair shape, easy floor to patch | $500 to $4,000 for under-slab repair; $200 to $2,000 for a broken pipe under the slab (Angi, 2024) |
| Reroute | Abandon the leaking line in the slab and run a new one through walls and the attic | Repeat leaks on the same line, or leak under costly flooring | $1,500 to $15,000 (Angi, 2024) |
| Whole-house repipe | Replace all supply lines, usually overhead, and abandon the slab lines | Leaks on several lines, old copper throughout | $1,500 to $15,000 (Angi) |
| Main water line repair | Repair the line between the meter and the house | Leak outside the house, found by closing the house shutoff | $330 to $1,360 (Angi, 2024) |
How we help you choose
- Where is the leak? Under a closet with carpet, a spot repair is simple. Under new stone tile in the kitchen, a reroute may cost less in the end.
- How many leaks so far? One leak is a repair. Repeat leaks mean the pipe is telling you something.
- How long will you stay? If you plan to keep the house for years, a reroute or repipe stops paying for the same problem twice.
- What does insurance cover? Ask your insurer before choosing; policies treat access, repair and damage differently.
Repeat leaks and full replacements are covered in detail on our whole-house repiping page. The overall published range for slab leak repair, from HomeAdvisor data via Angi updated April 2024, is $630 to $4,400.
Do slab leak repairs need a permit in Fountain Valley?
Stopping a leak can be permit-exempt, but replacing a defective concealed pipe counts as new work in Fountain Valley and needs a permit and inspection.
From the City's exempt work list
- Stopping leaks in drain, water, soil, waste or vent pipe is exempt
- But if a concealed pipe is defective and must be replaced with new material, it is new work and needs a permit
- Repairs that replace or rearrange valves, pipes or fixtures are not exempt
What that means for you
- Most slab leak spot repairs replace a section of pipe, so plan on a permit
- A reroute or repipe always needs a permit
- Gas piping in a slab has its own City handout and rules
The Building Division is at City Hall, 10200 Slater Ave, phone 714-593-4429, open Monday to Thursday, 7 a.m. to 6 p.m., closed Fridays. We pull permits for leak repairs that need them. See our permit guide for more.
Documenting a leak for your insurance claim
Good documentation starts before anything is opened: photos, meter readings, the detection report and itemized invoices give your insurer what it needs to review the claim.
- Photograph the meter readings from your two-hour test, with the time showing
- Photograph damp flooring, stains and damage before anything is moved or removed
- Keep the written leak detection report with the leak location, method used and readings
- Ask for photos of the pipe and the leak once it is exposed
- Keep itemized invoices that separate detection, access, pipe repair and floor or slab restoration
- Keep a copy of the City permit and final inspection
- Save water bills that show the jump in use
- Call your insurer early and ask what the policy covers for access, repair and resulting damage
We do not tell anyone what their policy covers. Coverage depends on your policy and your insurer. What we do is give you clear, itemized paperwork so the claim is easier to review. If water damage is spreading, call our 24/7 emergency line first; stopping the water comes before the paperwork.
Leak detection costs: published estimates
HomeAdvisor data published by Angi in April 2024 puts slab leak detection at $150 to $600, and these are national estimates, not our prices.
| Item | Published estimate | Source |
|---|---|---|
| Slab leak detection | $150 to $600 | HomeAdvisor via Angi, April 2024 |
| Slab leak repair, typical total | $630 to $4,400 | HomeAdvisor via Angi, April 2024 |
| Under-slab plumbing repair | $500 to $4,000 | HomeAdvisor via Angi, April 2024 |
| Rerouting lines around the slab | $1,500 to $15,000 | HomeAdvisor via Angi, April 2024 |
| Slab replacement | $3,600 to $8,000 | HomeAdvisor via Angi, April 2024 |
Detection is a small part of the total. What drives the repair price is the leak's location, the flooring over it, and whether one repair is enough. Our Fountain Valley plumbing costs guide has more published figures. You get a written price before work starts.
Other hidden leaks we find
Not every hidden leak is under the slab; many are in walls, cabinets, irrigation lines and fixtures.
- Toilet flappers that leak silently into the bowl
- Supply lines and angle stops under sinks, especially old braided or plastic connectors
- Shower valves and tub spouts leaking inside the wall
- Water heater connections and relief valve discharge; see water heater repair
- Irrigation lines and valves in the yard
- The main line between the meter and the house
We work on leaks across the city, from the 1960s and 1970s tracts in Central Fountain Valley to the older homes in North Fountain Valley and the townhomes and condos in East Fountain Valley, where a leak can reach a neighbor's unit quickly.
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 Fountain Valley homeowners ask
How do I know if I have a slab leak?
The clearest sign is a water meter that moves when no water is in use. Warm spots on the floor, the sound of running water, damp carpet and a sudden jump in your water bill are other common signs. A plumber confirms it with pressure tests and acoustic listening.
How do I test my water meter for a leak?
The EPA says to read your meter, use no water for two hours, and read it again. If the reading changed at all, you probably have a leak. Check toilets first, since a leaking flapper also moves the meter.
How much does slab leak detection cost?
HomeAdvisor data published by Angi in April 2024 puts slab leak detection at $150 to $600. Repair is priced separately and depends on where the leak is and which repair method you choose.
Is it better to reroute or repair a slab leak?
A first leak in pipe that is otherwise in fair shape is usually a spot repair. If the same line has leaked before, or the leak is under expensive flooring, rerouting it through the walls and attic often makes more sense. Several leaks on several lines point to a repipe.
Why do homes in Fountain Valley get slab leaks?
Many Fountain Valley homes were built in the 1960s and 1970s, when copper supply lines in or under the slab were typical. After 50 or more years of temperature changes and contact with concrete and soil, that pipe can develop pinholes. Hard water can be one contributing factor.
Does homeowners insurance cover slab leaks?
It depends on your policy. Call your insurer and ask what is covered for access, pipe repair and resulting damage. Keep meter photos, the detection report, damage photos and itemized invoices to support the claim.
Do I need a permit to fix a slab leak in Fountain Valley?
Usually, yes. The City exempts stopping leaks, but replacing a defective concealed pipe with new material counts as new work and needs a permit and inspection. Reroutes and repipes always need one. We pull the permit.
Who do I call if water is leaking near my water meter?
Call Fountain Valley City Water Services at (714) 593-4420, or the City's water emergency line at (714) 593-4485, so the City can check its side of the meter. If the meter test shows a leak inside the house or under the slab, call us at (657) 669-4766.
Sources
Facts on this page come from these public sources, checked October 31, 2026.
- EPA WaterSense, Fix a Leak Week
- City of Fountain Valley 2026 Consumer Confidence Report (2025 data)
- City of Fountain Valley, Water Quality Reports and FAQs
- City of Fountain Valley, Household Utilities Links
- City of Fountain Valley history
- City of Fountain Valley Building Division
- City of Fountain Valley, Work Exempt from Permits
- City of Fountain Valley, Permits and Handouts
- HomeAdvisor via Angi, slab leak repair cost (April 2024)
- Angi, cost to repipe a house
- This Old House, Fountain Valley plumbing costs
- Fountain Valley neighborhood guide
- SoCalGas: gas leak safety