Your water bill jumped and nothing in the house changed. You checked the faucets and the toilets and found nothing running. Everything looks normal, but under the concrete your house sits on, a water line may be leaking under pressure around the clock. That’s a slab leak, and its warning signs are easy to miss until real damage has been done.
A slab leak is a failed water line under the concrete foundation. Drain lines under the slab can fail too, and we cover how to tell the two apart below. A lot of Tulsa homes sit on slabs, and catching a leak early keeps the repair smaller and simpler.
Slab leaks leave clues. Here are the seven we’d want every homeowner to know, plus two free checks you can run today.
Why a slab leak gets worse every day
A water line under your slab is under pressure all day and all night, so a leak never takes a break. Every day it runs, it soaks more of the concrete, the flooring above it, and the soil below it. That’s why the repair and the mess both grow the longer it goes.
Leaks on the hot side are often caught sooner, because the heat comes up through the concrete and leaves a warm spot on the floor. Leaks on the cold side are quieter. They leave no warm spot, so they tend to run longer before anyone notices.
Signs 1 and 2: what you feel and hear
1. A warm spot on the floor
When a hot water line fails under the slab, the heat rises through the concrete into whatever flooring sits on top. Walk barefoot across tile or hardwood and notice whether one area feels warmer than the rest. It’s one of the earliest signs of a slab leak, and it often shows up before you see any water at all. Sunlight and heat ducts can warm a floor too, so treat it as one clue, not a verdict.
2. Running water you can hear with everything off
Turn off every faucet, make sure the dishwasher, washer, and ice maker are idle, and stand quietly in the middle of the house. A faint hiss or trickle from the floor or a nearby wall, with nothing running, is worth taking seriously. It doesn’t sound like a running tap, which is why most people shrug it off as the house settling. Listen near the bathrooms and the water heater, where the lines come together.
Signs 3, 4, and 5: what you can see and smell
3. Damp carpet or flooring that cups or lifts
Damp carpet in one spot, or wood and vinyl that starts to cup or lift with no spill to explain it, is a strong sign the water is coming from below. If the damp area isn’t under a bathroom or next to a fixture, the source is likely under the floor, not above it.
4. A musty smell in a room that never flooded
Water trapped under a slab can feed mold behind baseboards and under flooring long before you see it. A musty smell that hangs around one room, no matter the weather, is one of the most overlooked signs. It’s easy to blame humidity in a Tulsa summer, but a smell that stays put in one spot deserves a closer look.
5. New cracks in tile or along the floor
Water running under a slab can wash out the soil that supports it, and our Tulsa clay already moves with the wet and dry cycles. When the ground shifts, it shows up as new cracks in tile, grout lines, and drywall near the floor. Not every crack is a slab leak, but a new one that shows up alongside any other sign on this list deserves a plumber’s look, not a tube of caulk.
Signs 6 and 7: your water bill and your pressure
6. A water bill that jumped when nothing changed
Pull your last few water bills and compare them to the same months last year. If the bill climbed and your household habits didn’t change, water is leaving the system somewhere it shouldn’t. Check the toilets first, since a running toilet is the quietest water thief in a house. If they’re fine, your meter will tell you the rest.
7. Water pressure that dropped off
A leak on a supply line under the slab lets pressure escape before the water reaches your fixtures. If the whole house suddenly feels weaker at the faucets and shower, and nothing changed on the city side, a leak is worth ruling out. Pressure that fades slowly over years is a different story, and it’s often older pipe scaling up on the inside.
Two checks you can run today
The toilet check
Drop food coloring in each toilet tank, don’t flush, and look in the bowl in fifteen minutes. Color in the bowl means the flapper is passing water. That’s a cheap fix you can do yourself, and it rules out the most common reason for a high bill.
The meter check
- Shut off every faucet, the ice maker, and the irrigation, and make sure nothing else is using water.
- Find your water meter, usually in a box near the street, and watch the small triangle on its face.
- If the triangle is still moving, water is going somewhere.
- To narrow it down, close the main shutoff where the line enters the house and check again. If the meter still moves, the leak is in the line between the meter and the house. If it stops, the leak is inside the house, and that includes under the slab.
The meter tells you that water is leaving the system. It doesn’t tell you where. That takes a plumber with the right equipment, so don’t start cutting anything based on a meter test alone.
Is it a water line or a drain line?
Not every leak under a slab is on the pressurized side. A water line shows up as a water bill that jumped or a warm spot on the floor, and your meter keeps creeping with everything off. A drain line is quieter: repeat backups, or damp carpet in one spot. Drain lines get a camera inspection instead, and our sewer and slab services page covers that side.
When to call a licensed plumber
If you’ve noticed two or more of these signs, or your meter moves with everything off, don’t wait and see. A leak under your foundation costs more every day it runs.
When we come out, we isolate the hot and cold sides and pressure test each one, then pinpoint the leak with acoustic gear that hears water under concrete. On a drain line, a camera with a sonde on the head marks the spot and depth in paint on your floor. We don’t cut until we know where the leak is, and we walk you through your options and the cost before any work starts. You can read more about how we handle slab leak detection.
Tulsa Plumbing & Remodeling is licensed and insured (Oklahoma plumbing license #180753), and we offer same-day service. No pricing games.
The bottom line on slab leak signs
A warm spot, a hiss with everything off, damp flooring, a musty smell, new cracks, a jump in the bill, and a drop in pressure are all signs worth acting on. The toilet check and the meter check cost nothing and don’t take long. If they point to a leak, the next step is a licensed plumber who can find it without guesswork.
If any of this sounds familiar, call Tulsa Plumbing & Remodeling at (918) 800-4426.
