Signs you have a hidden leak
Not every leak announces itself with a puddle. Many run inside walls, under floors or beneath a concrete slab for weeks before anyone notices. Watch for:
- A water bill that jumps without a change in how you use water.
- The water meter moving when every faucet and appliance is off.
- Damp, stained or bubbling drywall, warped flooring, or a musty smell.
- Warm spots on a tile or concrete floor, which can point to a hot water line leaking under a slab.
- The sound of running water when nothing is on.
- Mold on baseboards or behind cabinets.
A simple test you can do yourself
Turn off every fixture and water-using appliance in the house, including the irrigation system. Look at the water meter and note the reading or watch the small leak indicator dial. Wait 30 minutes without using water, then check again. If the meter has moved, water is leaving the system somewhere. Next, close the main shutoff at the house and repeat. If the meter still moves, the leak is likely in the service line between the meter and the house. If it stops, the leak is inside.
Running toilets are one of the most common causes of hidden water use. Put a few drops of food coloring in the tank and wait 15 minutes without flushing. Color in the bowl means the flapper is leaking.
How plumbers find leaks
Professional leak detection aims to find the leak precisely so repairs disturb as little as possible. Common methods include:
- Pressure testing individual lines to isolate which one is leaking.
- Acoustic listening equipment that picks up the sound of escaping water through floors and walls.
- Thermal imaging to spot temperature differences from hot water leaks or damp areas.
- Moisture meters to map how far water has spread inside walls and floors.
- Camera inspection for drain and sewer lines.
Ask the plumber which methods they'll use and what the detection visit costs on its own, since detection and repair are often priced separately.
Repair options
- Spot repair. Opening the wall, floor or slab at the leak and replacing the damaged section. Usually the least expensive option when the rest of the piping is in good condition.
- Rerouting. Abandoning a leaking line under a slab and running a new line through the walls or attic instead. Often preferable to breaking concrete, especially if the piping is old.
- Repiping. Replacing the supply piping throughout the house. Worth considering when leaks keep recurring in aging pipe.
Water damage and mold
If water has been leaking for a while, the plumbing repair is only half the job. Wet drywall, insulation and subfloor need to dry thoroughly, and anything that stays wet can grow mold within a few days. Ask the plumber to show you how far the moisture has spread, and consider a water damage restoration company for anything larger than a small area. Document the damage with photos before repairs begin if you plan to file an insurance claim.
Questions to ask
- Where exactly is the leak, and how did you confirm it?
- Is the rest of the piping in the area in good shape?
- What are the options for repair, and what does each one involve?
- Who handles patching the wall, floor or slab afterward?
Preventing the next leak
High water pressure shortens the life of pipes, fittings and fixtures. Many homes have a pressure-reducing valve near the main shutoff; when it fails, pressure can climb without anyone noticing. A plumber can test your pressure with a simple gauge on an outdoor spigot.