Plumbing fixtures
How do you find a hidden water leak when nothing looks wet?
The quick answer
First compare water usage, not just the bill total. Then check accessible fixtures and take meter readings during a period with no intentional water use. Unexplained meter movement suggests water is passing through, but it does not tell you where the problem is.
In this guide
An unusually high water bill can send you looking for a puddle. But a toilet leaking into its bowl, an outdoor hose left flowing, or an automatic water-using system can increase consumption without leaving an obvious wet floor.
Use a few observations to narrow the question before assuming a pipe inside the wall has failed.
Did the price change, or did water use change?
Compare the volume used and the number of days in the billing period. A higher total charge does not automatically mean more water passed through the meter. Check rates, fees, and whether the reading was estimated or actual with your utility.
For an example using made-up numbers, 6,000 gallons over 30 days equals 200 gallons per day. The same 6,000 gallons over 20 days equals 300 per day. Comparing equal daily use helps separate a longer billing period from a real increase.
Then note changes in the household: visitors, watering, a filled pool, extra laundry, or an appliance schedule. These are possibilities to check, not proof that the plumbing is sound.
What can a meter check tell you?
EPA WaterSense recommends comparing meter readings across a two-hour period without water use. Make a note or photo of the reading at each end of the interval.
Account for automatic users such as irrigation, softener regeneration, ice makers, or scheduled appliances. If you cannot establish a quiet period, tell the utility or plumber which systems may have operated. Use an accessible household meter display; do not open utility equipment or remove a heavy street cover.
An unexplained change suggests water was passing through the meter. It does not reveal the exact fixture, pipe, or location. A stable reading during one quiet period also cannot rule out an intermittent leak that was inactive at the time.
Where should you look first?
Inspect only places you can see without disturbing plumbing or finishes:
| Place | Useful observation |
|---|---|
| Toilets | Refill sounds between uses or water moving in the bowl. |
| Under sinks | Fresh droplets, damp stored items, or staining that returns. |
| Appliance connections | Visible moisture near accessible supply hoses. |
| Water heater | Moisture near connections, the valve discharge, or the base. |
| Outdoor fixtures | A running hose, dripping hose bibb, or unexpected water use. |
For toilet observations, use our running-toilet guide. If moisture is near the heater, follow the water-heater leak guide rather than keeping the heater operating to see what happens.
Does a wall stain prove a water-supply pipe is leaking?
No. Record whether it appears after using a particular fixture, during rain, or continuously. Those are different clues. A photograph of a stain cannot distinguish a supply leak, drainage issue, or another moisture source on its own.
Do not cut into walls or ceilings based only on the meter result. Share the timing and visible changes with the appropriate professional so the source can be investigated. Stay clear of sagging ceilings and wet electrical equipment. Active uncontrolled water needs immediate attention; do not wait two hours to complete a meter experiment.
Can a thermal camera find a leak behind a wall?
A thermal camera measures surface-temperature patterns; it does not see through the wall or directly photograph water inside it. Moisture can change those patterns, which gives an investigator a clue about where to check next.
FLIR’s guide to detecting moisture explains that the method depends on the conditions and interpretation. A colored patch on a thermal image is not a complete diagnosis. Ask what evidence supports the suspected source and how it will be confirmed before agreeing to open a finished surface.
Who handles a leak at the water meter?
Responsibility depends on the utility and the location of the leak. Naperville’s water-meter guidance explains the city’s repair boundary and provides its Water Utility contact. It also notes that condensation on a meter can occur, so moisture alone does not identify a failed connection.
If you are served by another utility, ask that utility about its boundary instead of applying Naperville’s rules to your address. Photograph what you can see without touching fittings or utility seals.
Would a leak alarm help?
A moisture sensor detects water where the sensor sits. A flow-monitoring device watches water use and can flag unusual patterns. Some systems can operate a shutoff valve; that feature is not included in every device.
The EPA’s leak-detection and flow-monitoring guide explains these differences. A dry sensor does not prove the whole house is leak-free, and an alert still needs investigation. Discuss coverage, alerts, power, maintenance, and compatibility before selecting a system.
What should you tell the plumber?
Bring the dated bill or meter observations, any change in household use, photos, and the timing of sounds or moisture. These details create a clearer starting point than “the bill seems high.”
For help with fixture and plumbing concerns in Accurate’s service area, request service. Explain what you observed so the team can confirm the appropriate next step.
