Where hidden leaks can start
Possible sources include supply lines behind toilets and sinks, shower valves inside walls, pipe joints above ceilings, drain lines under tubs and water lines under the slab. Some leak only when a fixture is used, which can make them harder to spot.
How leaks are located
Common methods include moisture meters, which can map how far water has spread through drywall and flooring, thermal imaging, which can show cooler or warmer areas where water is present, and pressure or flow tests, which can help separate supply leaks from drain leaks. Ask the plumber which methods they plan to use.
Why finding the source matters
Drying out a stain or replacing drywall without fixing the leak can hide the problem until it returns. Locating the source first can help avoid repeat repairs and keep any opening small.
A quick check you can do first
Turn off every tap, toilet and water-using appliance, then look at your water meter. If the leak indicator keeps moving, water may be escaping somewhere. Note the reading, wait an hour without using water and check again.
What happens when you call
- 1
Describe what you see
Describe the stain, smell, sound or damp area and where it is.
- 2
Confirm the leak
A plumber may check the meter and test the lines to confirm whether water is escaping.
- 3
Find the source
Moisture mapping, thermal imaging and testing can help trace the water back to the leaking pipe or fixture.
- 4
Review repair options
Ask for the repair options to be explained, including how small the opening can be, before work starts.