The most reliable sign of a hidden water leak is a water meter that keeps moving when nothing in the house is using water. Other common signs include an unexplained jump in the water bill, warm spots on tile floors, the sound of running water, musty odors, and stains or bubbling on walls and ceilings.
The 30-minute water meter test
- Turn off every faucet, shower, irrigation zone and water-using appliance. Make sure no toilet is refilling.
- Find your water meter, usually in a box near the street. Note the reading or watch the small leak indicator dial, often a triangle or star.
- Wait 30 minutes to an hour without using any water.
- Check the meter again. If the reading changed or the indicator moved, water is leaving the system somewhere.
To narrow it down, close the main shut-off at the house and recheck. If the meter stops, the leak is inside the home. If it keeps moving, the leak may be in the line between the meter and the house or in irrigation.
Warning signs inside the house
Warm spots on the floor
Most Florida homes are built on concrete slabs, with water lines running in or under them. A hot water line leaking under the slab can warm the tile above it. A floor spot that feels noticeably warmer than the surrounding area is a classic slab leak sign.
Running water sounds
If you hear water flowing when everything is off, it’s worth investigating, especially near walls with plumbing or on the floor.
Stains, bubbling paint and soft drywall
Water traveling inside walls or ceilings shows up as discoloration, peeling or bubbling paint and soft spots. In a condo, a ceiling stain can come from the unit above.
Musty smells and mold
South Florida’s humidity speeds up mold growth. A persistent musty odor in one room, inside a cabinet or along baseboards can mean moisture you can’t see.
Cracked or lifting tile, swollen baseboards
Moisture under flooring can cause tile to crack or loosen and wood baseboards to swell.
Water heater running constantly
If the heater seems to run all the time, a leak on the hot water side could be the reason.
Signs outside the house
- A patch of lawn that stays wet or unusually green
- Water pooling near the foundation or driveway when it hasn’t rained
- Cracks in pavement over the water line path
Why hidden leaks matter in Boca Raton
A small leak can waste a surprising amount of water over a month, and the damage it causes, including rotted cabinets, ruined flooring and mold, usually costs more than the plumbing repair. In condo buildings, a leak can also affect neighbors. Finding it early keeps both costs and disruption down.
How professionals find leaks
Plumbers use pressure testing to confirm and isolate a leak, then acoustic listening equipment, thermal imaging and moisture meters to pinpoint it, often to within a small area, before any tile or drywall is opened. Learn more on our leak detection page, and if the pipes are failing in more than one place, read about pipe repair and repiping.
If your meter test shows a leak, call (561) 794-0131 and we’ll connect you with an independent Boca Raton plumber.
Frequently asked questions
How can I tell if I have a leak under my slab?
Warm floor spots, running-water sounds, a moving meter with everything off and a rising water bill are the most common signs. A plumber can confirm with pressure testing and acoustic tools.
Can a toilet cause a hidden leak?
Yes. A running toilet leaks water into the bowl and down the drain, which shows up on your meter and bill. Add food coloring to the tank; if color appears in the bowl without flushing, the flapper is leaking.
Does a high water bill always mean a leak?
Not always. Irrigation changes, guests or seasonal use can raise bills. The meter test helps confirm whether there’s a leak.
Is a hidden leak an emergency?
If water is actively damaging floors, walls or a neighbor’s unit, treat it as urgent and shut off the water. Otherwise, schedule leak detection promptly.