Start with the easy suspects
A slab leak is one possible explanation for a high bill or a damp floor, but it is rarely the most common one. Running toilets, irrigation problems and leaks in the yard are all more frequent, and all are easier to check. Working through them first means that if a slab leak is the answer, you will know it with more confidence.
In Yorba Linda, where many lots have automatic sprinklers, irrigation is especially worth checking before anything else.
Common look-alikes
| Possible cause | Typical clues | How to check |
|---|---|---|
| Running toilet | Tank refills on its own, faint hiss in the bathroom | Food coloring in the tank; close the toilet's valve and recheck the meter |
| Irrigation leak | Soggy spots in the yard, high summer bills | Turn off the irrigation controller and recheck the meter |
| Service line leak | Wet area between the street and the house, meter moves with house main closed | Close the house main and watch the meter |
| Shower pan or tub leak | Damp only after showers, stains near the bathroom | Avoid using that shower for a day and see if it dries |
| Drain leak | Damp or odor after draining sinks or tubs, meter still | Drain leaks do not move the meter; note when dampness appears |
| Supply line in a wall | Stain or bubbling paint higher up a wall | Look for staining above floor level |
| Water heater or softener | Water around the unit, softener cycling | Inspect around the units and bypass the softener during tests |
An elimination order that works
- Turn off irrigation.Switch the controller off and close any irrigation shutoff.
- Run the meter test.With all fixtures off, watch the leak indicator.
- Isolate toilets.Close each toilet's supply valve and check the meter again.
- Close the house main.If the meter still moves, the leak is likely between the meter and the house.
- Isolate the hot side.With the main open, close the water heater's cold inlet. A stop points to a hot line.
- Call for leak location.If the meter moves with fixtures, toilets and irrigation ruled out, have a licensed plumber locate the leak.
Where your results point
- IfMeter still, dampness only after showers or drainingThenLikely a drain or shower pan issue, not a slab supply leak.
- IfMeter stops when irrigation is offThenAn irrigation leak. Check valves and lines in the yard.
- IfMeter moves with the house main closedThenThe service line in the yard is the likely source.
- IfMeter moves with everything ruled out, house main openThenA leak inside the home or under the slab is likely. Book leak location.
Common questions
Can a drain leak under the slab cause a wet floor?
Yes. Drain lines also run under slabs, and a drain leak can dampen flooring. It will not move the water meter, which helps tell it apart.
Whose responsibility is a leak in the yard?
Generally the line from the meter to the house is the homeowner's, while the meter and the street side belong to the provider. Contact your water provider if you think the leak is on their side.
What if I cannot find any cause?
Intermittent leaks can be tricky. Repeat the meter test at different times, and share your notes with a licensed plumber.
General information for Yorba Linda, not a quote or professional advice. In an emergency, call 911.