A small leak almost never stays small. What starts as a faint drip under a sink, a damp spot on a wall, or a smell that comes and goes can quietly turn into stained ceilings, warped floors, mold, and a repair bill that’s a fraction of what it would’ve been if someone caught it three months earlier.
I see this constantly — a leak that’s been running behind a wall or under a slab for weeks before anyone notices. Here’s what to watch for.
The Early Warning Signs
A water bill that climbs for no clear reason.
If your usage hasn’t changed but the bill keeps creeping up over two or three months, water is going somewhere it shouldn’t. A pipe behind a wall or under a slab can waste a surprising amount before it ever becomes visible.
Damp spots that keep coming back.
A wet patch under a sink, around a toilet base, along a wall, or on a ceiling that you wipe up once and it returns — that’s not a one-time thing, that’s an active source. Check under sinks, around tubs and showers, near water heaters, along baseboards, and on ceilings below upstairs bathrooms.
Stains on walls or ceilings.
Brown, yellow, or dark stains mean water has been sitting somewhere for a while, even if the spot looks dry today. Ceiling stains especially point to a line above — an upstairs bathroom or a pipe run I need to trace.
A musty smell that won’t go away.
Trapped moisture creates the exact conditions mold and mildew need. If a room keeps smelling stale no matter how much you air it out or clean it, there’s usually a leak feeding it — even before you can see any growth.
Peeling paint or bubbling walls.
Water behind a painted surface makes it bubble, peel, or feel soft to the touch. If there’s a pipe run behind that wall, water damage is the likely cause, not old paint.
Where Small Leaks Usually Start
Under kitchen and bathroom sinks, around toilet supply lines, behind washing machines, near water heaters, around tubs and showers, at pipe joints and shut-off valves, and at outdoor hose bibs. These are the spots with the most frequent water use and pressure changes, so they’re where I check first.
How I Actually Find It
A visible drip is easy. A leak inside a wall or under a slab isn’t — and guessing where to cut open drywall or break concrete is how a small problem turns into an expensive one. When I suspect a hidden leak, I use a Mileseey TR20 thermal camera to spot temperature differences first, confirm with a moisture meter, then trace the exact line with a Pulsar 2000 line tracer and pinpoint the precise spot with a geophone before anything gets opened up. One cut, not a search pattern. If you want the full rundown on how that process works, see my slab leak detection page.
What to Do Right Now
If you’re seeing any of these signs: check under sinks and around fixtures for moisture, watch your water bill for unexplained jumps, look at ceilings and walls for new staining, and if you find an active, visible leak, shut off water to that fixture. Beyond that, it’s worth having it looked at properly rather than waiting to see if it gets worse — it usually does.
Waiting on a small leak almost always costs more than catching it early: bigger repair bills, more damage to walls and flooring, mold remediation, and water you’re paying for but never using. Catching it early is one of the cheapest things you can do for your home.
If something feels off, call 239-388-3631 or reach out here — I’ll walk through it with you and, if it makes sense, run the equipment before we talk about a fix.