The most expensive water damage is often the kind nobody sees until it's been going on for weeks. A slow drip inside a wall, a leaking drain under the house or condensation in the attic can rot framing and grow mold long before a stain shows up. Here are the signs to watch for, simple ways to check, and what to do if you find something. For urgent problems, see our page on water damage restoration in Kennesaw, GA.
Signs of hidden water damage
- A musty smell that comes back no matter how much you clean, especially in one room or near the floor.
- Stains and discoloration on ceilings and walls, often yellow or brown rings that grow over time.
- Bubbling, peeling or blistering paint and wallpaper.
- Floors that feel soft, spongy or uneven, or hardwood that cups or buckles.
- Baseboards and trim that swell, separate or pull away from the wall.
- Mold spots in corners, around windows or behind furniture.
- A water bill that jumps without any change in how you use water.
- The sound of running water when everything is off.
Where hidden leaks start
- under kitchen and bathroom sinks, at supply lines and drain connections
- behind toilets and dishwashers, and at refrigerator ice maker lines
- at washing machine hoses and the water heater
- in the crawl space, where supply and drain lines run under the floor
- in the attic, where an air conditioning condensate line or pan can overflow
- around windows, doors and the roof after heavy rain
Simple ways to check
The water meter test
Turn off every faucet and water-using appliance, then look at your water meter. If it keeps moving, water is going somewhere. Check it again after an hour with nothing running for slower leaks.
The toilet dye test
The EPA's WaterSense program suggests adding a few drops of food coloring to the toilet tank and waiting 10 minutes without flushing. If color shows up in the bowl, there's a leak, often fixed by replacing a worn flapper. WaterSense estimates that leaks can waste close to 10,000 gallons a year in an average home.
A look under the house
Open the crawl space access with a flashlight and look for standing water, wet soil, sagging insulation or a torn vapor barrier. See crawl space water removal if you find any.
How professionals find hidden moisture
Restoration contractors use moisture meters, which read moisture inside drywall, wood and concrete, and thermal imaging cameras, which show temperature differences that often point to wet areas. Neither replaces opening the wall when readings say something is wrong, but they narrow down where to look and how far the water has spread. Once the source is fixed, structural drying brings the materials back to normal.
What to do if you find a hidden leak
Stop the source
Shut off the fixture or main valve, or call a plumber if you can't find it.
Document it
Photograph the stain, the leak and any mold before anything is opened up.
Call your insurer
Ask about coverage. Policies often treat sudden leaks differently from long-term seepage.
Dry and check for mold
A contractor can open the area, dry it and address mold if it's started.