The short answer
Check Your Water Bill
Your water bill is a simple early warning system. Compare this month's usage to the same period last year. A sudden jump with no change in your household habits often points to a hidden leak.
Small leaks can waste hundreds of gallons over time. If the bill climbs 10 percent or more, investigate. Keep a record of your monthly usage so you can spot changes quickly. Also note the date you last had the meter read, in case the increase is due to a billing error rather than a leak.
- Look for a spike of 10 percent or more
- Compare to the same month last year
- Check for a running toilet or dripping faucet first
- Turn off all water and watch the meter for an hour
Listen for Running Water
Stand still in a quiet room and listen. A faint hiss or drip behind walls or under floors can mean a pipe is leaking. Turn off all taps, flush toilets, and shut off appliances that use water, then listen again. You might also hear a soft whoosh from a toilet that runs intermittently, which could indicate a flapper valve issue.
If you still hear water moving, the leak may be inside a wall or slab. This is a good time to call local water damage pros for an inspection. They have tools to locate the source without tearing open your home.
Look for Stains and Warping
Inspect ceilings, walls, and floors for discoloration, bubbling paint, or sagging drywall. Water stains often appear as yellow or brown patches. Warped or buckling floorboards can signal a leak beneath the surface.
Check around toilets, under sinks, and near appliances like the dishwasher, refrigerator, or water heater. A damp spot that never dries out is a red flag. Feel walls and floors for coolness or moisture, which can indicate hidden water. Pay attention to the base of your toilet; if the floor feels spongy or the tile is loose, water may be seeping from the wax ring.
Notice Musty Odors
A persistent musty smell, even in a dry room, often means mold is growing where water has collected. Mold thrives in damp, dark spaces like behind baseboards or under carpet. The odor can spread through vents, making it hard to pinpoint.
If you smell something earthy or sour, search for the source. Check the attic, crawlspace, and around windows. If you can't find it, a water damage inspection can help. Mold can affect indoor air quality, so see a doctor if you feel unwell. Also, a musty smell in a closet or behind furniture might point to a slow leak from a pipe in the wall.
Monitor Your Meter
Your water meter is a direct tool. Turn off all water inside and outside your home, then check the meter dial. If it moves or spins while nothing is running, you have a leak. Leave it off for an hour and check again to confirm.
This test works for most homes. If the meter shows activity, the leak is between the meter and your fixtures. Write down the shutoff valve location so you can stop water fast in an emergency. If you live in Fresno, keep that note handy. For homes on a well, the pressure tank may cycle on and off; that can indicate a leak in the supply line as well.
Talk to someone now
Call (559) 272-9793 any time, day or night, and describe what happened.
Call Now (559) 272-9793Frequently asked questions
What is the most common sign of a hidden leak?
An unexplained rise in your water bill is often the first clue. A leak that drips once per second can waste over 3,000 gallons a month. That shows up as a noticeable increase in your bill, even if you don't see water yet.
Can a hidden leak cause structural damage?
Yes. Water seeps into wood, drywall, and insulation, weakening them over time. It can rot joists, rust metal, and stain ceilings. The longer you wait, the more repairs you may face. Acting quickly reduces the chance of serious structural issues.
How do pros find hidden leaks?
The pros use moisture meters, thermal cameras, and acoustic listening devices to locate leaks behind walls, under floors, or in slabs. They can trace water paths without tearing things apart. You can do basic checks, but a professional inspection gives a clear answer.
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