What the owner noticed
In this example, the carpet along a bedroom wall in a Yorba Linda home feels damp, and the baseboard has started to swell. On the other side of that wall is a shower. The owner has read about slab leaks and fears the worst.
The first test is the meter. With every fixture off, the leak indicator does not move, even after half an hour. That is an important clue: a pressurized supply leak, under the slab or anywhere else, would normally keep the meter moving.
How the owner narrowed it down
- Meter test.Meter still with fixtures off. A constant supply leak is unlikely.
- Stopped using the shower.For two days the household used another bathroom.
- Watched the baseboard.The dampness began to dry without shower use.
- Tested the shower.A single shower brought the dampness back the next morning.
Supply leak vs shower-related leak
Supply leak under the slab
- Meter moves with fixtures off
- Dampness persists regardless of use
- May come with a warm floor if hot side
Shower pan or drain leak
- Meter still with fixtures off
- Dampness follows shower use
- Often near the shower wall
What the owner did next
Common questions
Is this a real case?
No. It is an invented example.
Can a drain under the slab leak too?
Yes. Drain leaks also do not move the meter, which is why a plumber may test the drain separately.
Could it still be a slab leak?
An intermittent supply leak is possible but less likely here. Repeat the meter test on different days to be sure.
General information for Yorba Linda, not a quote or professional advice. In an emergency, call 911.