Some leaks are obvious. Others hide inside walls, under floors or beneath the slab, wasting water and causing damage for months. Modern leak detection finds these hidden leaks without tearing the house apart, so repairs can be quick and targeted.
Sifixit is a free referral service. Call the number on this page and you will be connected with an independent plumbing provider where one serves your area. Calling costs nothing and you are never obliged to hire anyone.
Signs of a hidden leak
These are the most common signs of a leak you cannot see.
- A water bill that rises with no change in use
- The sound of running water when everything is off
- Warm spots on floors, which can mean a hot water slab leak
- Damp, stained or bubbling walls and ceilings
- A musty smell or mold in one area
- Low water pressure
What to do right now
If water is near outlets or the electrical panel, stay out of it and switch off the power only if you can reach the panel safely.
- Check your water meter with every tap and appliance off
- If the meter keeps moving, you likely have a leak
- Shut off the main valve if water is escaping
- Note where you see stains, damp or warm spots
- Take photos for your insurer
- Call a plumber with leak detection equipment
How leaks are found
Acoustic listening
Sensitive microphones pick up the sound of water escaping from a pipe.
Thermal imaging
Cameras show temperature differences, which can reveal hot water leaks and damp areas.
Pressure testing
Sections of pipe are tested to see which one is losing pressure.
Moisture meters
Meters confirm where walls, floors and ceilings are wet.
How leaks are repaired
- The plumber pinpoints the leak before opening anything.
- A small opening is made in the wall, floor or slab at the leak.
- The damaged section of pipe is repaired or replaced.
- For slab leaks, the pipe may be rerouted through walls or the attic instead.
- The area is tested, and any water damage is dried.
Catching leaks early
- Check your water meter once in a while with everything off
- Watch your water bill for unexplained jumps
- Look under sinks and around toilets regularly
- Consider leak detectors near the water heater and washing machine
- Know where your main shut off valve is
Questions to ask before you hire
- What equipment do you use to find hidden leaks?
- How much will you need to open walls or floors?
- Should the pipe be repaired, rerouted or replaced?
- Will you check for water damage after the repair?
- What warranty do you give on the repair?
Frequently asked questions
How do I check for a leak with my water meter?
Turn off every tap and water using appliance, then watch the meter. If it moves or the leak indicator spins, water is escaping somewhere.
What is a slab leak?
A leak in a pipe under a concrete slab foundation. Signs include warm spots on the floor and a rising water bill.
Does insurance cover leak detection?
Some policies help pay to find a leak when it caused covered water damage. The pipe repair itself is often not covered.
Can leaks be found without breaking walls?
Usually, yes. Leak detection equipment narrows the location so only a small opening is needed.
Learn more
Our main plumbing guide covers the wider picture, including what affects the cost and when to call a professional.
Sifixit is a free referral service and does not provide home services. Calls may be answered by a partner call center or connected directly to independent local providers, who are solely responsible for their work, pricing, licensing and insurance.