Is This Really a Slab Leak?
Not every wet floor or unexplained water bill points to an under-slab pipe failure. Here is how to read the signals specific to Perris homes and decide whether to call for detection.
(951) 416-3250What a Slab Leak Actually Is
A slab leak is a break or pinhole in a supply or drain pipe that runs through or directly beneath your home’s concrete foundation. Because the pipe is encased in concrete, the leak does not drain visibly to the surface or inside a wall cavity. Instead, water travels upward through the concrete or outward through the soil below the foundation.
In Perris, the local soil profile makes slab leaks behave differently than they do in other parts of Southern California. The clay-heavy alluvial soil in the 92570 and 92571 zip codes absorbs moisture slowly and expands when saturated. A pipe leaking 1 or 2 gallons per hour can go unnoticed for weeks while progressively undermining the soil around the foundation footing.
The signs below are the ones that reliably distinguish a slab leak from more common plumbing failures. None of them alone is definitive, but two or more together — especially in a home built before the mid-1990s when copper supply lines were standard — should prompt a detection visit.
Six Signals That Point to an Under-Slab Leak
Each of these has a straightforward explanation rooted in how under-slab water behaves in Perris homes.
Your Water Meter Does Not Stop
With every faucet, shower, toilet, and appliance off, the water meter dial or digital flow indicator should be completely still. If it continues to move, water is exiting the system somewhere. This test takes about 15 minutes. The small triangular leak indicator on most EMWD meters is especially sensitive and can detect a drip as slow as 0.1 gallons per minute.
Strong indicatorOne Spot on the Floor Feels Warm
Hot water supply lines typically run just below the surface of the concrete. A pinhole in one of these lines creates a localized warm patch in the floor. Unlike radiant heat, which is uniform across a zone, a slab leak warm spot is usually 12 to 24 inches in diameter and noticeably warmer than the surrounding floor. Tile is the easiest material to feel this through.
Strong indicatorEMWD Bill Climbed Without Explanation
A sudden 30% or more increase in your water bill, with no change in household habits or outdoor irrigation, is a reason to check the meter. EMWD billing is tiered, so a leak that pushes usage into a higher tier can cause a bill increase larger than the volume of water lost would suggest. Compare usage in hundred cubic feet (HCF) on two consecutive bills, not just the dollar amount.
Strong indicatorYou Hear Water Moving When Nothing Is Running
A pressurized supply line leak creates a faint hissing or rushing sound that can sometimes be heard through the floor or at the wall near the meter shutoff. This is easier to detect in quiet conditions, such as early morning. The sound is usually low-pitched and consistent rather than intermittent, which rules out a running toilet or a slow-fill valve.
Possible indicatorA Section of Floor Is Wet or Damp
When water saturates the soil beneath the slab and cannot drain quickly enough, it begins to wick upward through cracks or control joints in the concrete. The result is a damp patch on a floor that has not been spilled on. In Perris homes with tile floors, grout lines are often the first place this moisture appears. Carpet may feel spongy or have a persistent musty smell in a specific area.
Strong indicatorMold or Mildew at the Base of Walls
Moisture migrating up through the slab tends to collect against wall framing. This creates conditions for mold growth at the very bottom of walls, often behind baseboards. Unlike ceiling or upper-wall mold caused by roof leaks or condensation, slab-sourced mold is concentrated in a horizontal band near the floor. A musty smell without visible mold suggests moisture inside the wall cavity.
Possible indicatorSlab Leak vs. Other Plumbing Problems
These symptoms can overlap with roof leaks, condensation, or fixture failures. This table shows what usually distinguishes each cause.
| Symptom | Points to a Slab Leak When | More Likely Something Else When |
|---|---|---|
| Wet floor or carpet | The wet area has no water source above it and does not dry between usages | Located directly under a sink, appliance, or plumbing fixture |
| High water bill | Bill is up but meter confirms water moving with all fixtures shut off | Bill is up but meter stops when fixtures are off — likely a running toilet |
| Water sound inside home | Sound is in the floor or lower wall, constant, and present with everything off | Sound is in upper walls or ceiling, intermittent, tied to toilet fill or pressure relief valve |
| Warm floor spot | Localized single spot, cooler surrounding floor, no underfloor heat system | Uniform warmth across a zone — likely a radiant system, not a leak |
| Mold at baseboard level | Mold appears in a horizontal band at floor level, interior walls, no roof or window issue | Mold is on exterior walls near windows or appears near ceiling — likely condensation |
| Foundation cracks | New cracks appearing alongside wet floor symptoms in a home with aging copper | Cracks present for years with no wet-floor signs — often normal settlement |
The Water Meter Test You Can Do Right Now
This test takes about 20 minutes and gives you a clear yes or no on whether water is leaving your system while nothing is running.
Turn Off Everything That Uses Water
Shut off all faucets, showers, and hose bibs. Make sure the washing machine, dishwasher, and refrigerator ice maker are not mid-cycle. Check that any irrigation system is off. If you have a tankless water heater, no special steps are needed, but a tank-style heater refilling can create a false positive, so note whether you recently used hot water.
Locate Your Water Meter at the Street
In most Perris properties, the EMWD meter is in a box at the curb or near the sidewalk. Open the plastic cover. You will see either a spinning dial (older meters) or a digital display with a flow indicator light or triangle. Some meters also have a small red or blue leak detection triangle that spins even with tiny flows.
Note the Reading and Wait 15 to 20 Minutes
Write down the numbers shown on the meter, or take a photo. Wait 15 to 20 minutes without using any water in the house. Do not flush toilets during this window.
Check the Meter Again
If any dial or indicator has moved, water left the system. The leak detection triangle spinning continuously, even slowly, is confirmation of an active leak. Note the difference in readings. A change of more than 0.1 HCF in 20 minutes suggests a moderate to large leak that could easily be an active slab pipe failure.
Rule Out the Main Shutoff
If the meter moved, close the main shutoff valve (usually near the meter or at the side of your house). Check the meter again. If it stops, the leak is inside your property. If the meter still moves, the leak is between the meter and your shutoff, which is still your responsibility as the property owner in most Perris parcels.
What to Do Based on What You Found
The meter test and the signs above should give you a clearer picture. Here is how to act on each outcome.
Schedule a Detection Visit
- Call and describe both the meter result and any floor or wall symptoms
- We use acoustic ground microphones and thermal cameras to pinpoint the location through the slab
- Detection is done in a single visit with no concrete removed
- You receive a written scope of the pipe location before any repair work begins
Still Get It Checked
- An active leak with no surface signs usually means it is still running through soil below the slab
- Water that has not surfaced yet is still eroding foundation soil and increasing repair cost over time
- Detection visit can confirm location even before surface moisture appears
- Catching it early keeps repair options broader — rerouting and trenchless lining are both available
Check Fixtures First
- A toilet that runs between flushes is the most common cause of a moved meter when the leak stops at the shutoff
- Check the fill valve and flapper in each toilet tank
- Inspect supply lines and shutoff valves under sinks for slow drips
- If nothing is found and symptoms return, call for a second meter test with a plumber present
What to Expect When You Call
We serve Perris properties in 92570 and 92571, 24/7.
Acoustic and Thermal Detection
We use ground microphones and thermal imaging to locate the pipe failure through the slab without breaking concrete.
Written Scope Before Work
You receive a written description of the pipe location and proposed repair method before any concrete is touched.
Local Perris Knowledge
We know the soil conditions, pipe ages, and water pressure history in Perris neighborhoods from Rancho El Dorado to South Perris.
Multiple Repair Options
We offer spot repair, pipe rerouting, trenchless epoxy lining, and full repipe — the best fit for your pipe age and layout.
Frequently Asked Questions
How do I know if I have a slab leak or just a regular plumbing leak?
Can I check for a slab leak myself before calling a plumber?
Is a warm spot on the floor always a slab leak?
What does mold near the floor mean?
How quickly do slab leaks get worse?
Learn More About Slab Leaks in Perris
We serve these Perris areas:
Think You Have a Slab Leak?
Call us and describe what you found. We will tell you whether a detection visit makes sense before you commit to anything.
(951) 416-3250Request a Callback24/7 Availability | Perris CA 92570 / 92571