A Sudden Water Bill Increase May Point to a Leak Under the Slab
If your water bill jumped and your household has not changed its routine, start by assuming water is going somewhere it should not. A leak under the concrete slab is one possibility, especially when the meter keeps moving with every faucet, appliance, irrigation zone, and hose bib turned off. It is not the only cause, though. A running toilet, a failed irrigation valve, a dripping pressure-relief valve, or a water softener stuck in a regeneration cycle can waste thousands of gallons before anyone sees a puddle.
Look at the usage numbers on the bill, not just the dollar total. A higher rate, sewer charge, or billing adjustment can raise the amount due without a major increase in gallons used. If the bill shows 12,000 gallons last month and 28,000 gallons this month, that is a water-use problem worth tracking down. For comparison, a leak of only 0.1 gallon per minute can lose about 4,300 gallons over 30 days.
Check the meter before you assume it is under the slab
Turn off faucets, washing machines, dishwashers, ice makers, irrigation controllers, pool-fill lines, and anything else that uses water. Then find the water meter, usually near the street or property line, and watch the small leak indicator or sweep hand for 15 to 30 minutes. If it moves while everything is shut down, water is passing through the meter somewhere on the property.
Take a photo of the meter reading, wait 30 minutes, and take another photo. Even a small change matters when no water should be running. If the meter does not move during that test, the high bill may be tied to irrigation running at another time, a toilet that cycles intermittently, or a water-using appliance that only leaks while operating.
Toilets deserve a separate check because a bad flapper can be silent. Put a few drops of food coloring in the tank and wait 15 minutes without flushing. If color reaches the bowl, the flapper or flush valve is leaking. Also look under sinks, behind the refrigerator, around the water heater, and at outdoor hose connections for fresh moisture, white mineral buildup, or a steady drip.
Signs that point more strongly to a slab leak
A slab leak is a leak in a water line running beneath the concrete foundation. Homes with copper supply lines can develop pinhole leaks after years of water flow and pipe wear, but leaks can also occur at fittings, joints, or damaged plastic piping. The water may stay beneath the slab, travel through soil, or come up at a crack or floor edge instead of appearing directly above the damaged pipe.
Warm spots on a tile, vinyl, or concrete floor can point to a hot-water line leak. Walk barefoot across the floor in the early morning, when the house is cooler, and pay attention to one area that feels noticeably warmer than the surrounding floor. A hot leak can also make the water heater run more often, even when nobody has used hot water for several hours.
Other clues include the sound of faint rushing or hissing when the house is quiet, damp carpet near a wall, buckled flooring, loose vinyl planks, or a musty smell that returns after cleaning. You may also see a wet strip along the outside edge of the slab or unusually green grass in one small area. None of these signs proves the exact location, but several together make an under-slab line more likely.
If you shut off the valve above the water heater and the meter stops moving, the leak may be on the hot-water side. If the meter continues moving with that valve closed, the issue may be on a cold-water line, irrigation branch, toilet supply, or another line still connected to the main. This is useful information for the plumber, but do not force a stuck valve or turn valves repeatedly if they are old and corroded.
What happens after a leak is found
A plumber can isolate sections of the plumbing system, check pressure loss, and locate the likely leak area before opening flooring or concrete. The exact approach depends on whether the problem is a hot line, cold line, drain line, or irrigation pipe. There is more detail in the leak detection process behind walls, which uses similar steps of narrowing down where water is traveling before materials are opened.
Once the plumbing leak is repaired, check the meter again with all water fixtures off. The leak indicator should remain still during a 15- to 30-minute check. Keep photos of the meter reading, the high bill, any wet flooring, and visible staining. Those details help show whether the water use stopped after the repair.
Water that has been under flooring or inside wall materials for more than 24 to 48 hours can leave swelling, staining, odor, or hidden dampness even after the pipe is fixed. Drying may involve removing wet padding, lifting affected flooring, using air movement, and checking moisture in the lower wall area. For water damage caused by a plumbing leak, Residential plumbing services in Leander can help identify the next steps for the affected area.