Same symptom, different problem
The meter only knows that water is leaving. A toilet flapper that leaks into the bowl, an irrigation valve weeping into a planter, or a break in the line between the meter and the house all make the meter move exactly as an under-slab leak does. Some of these are quick fixes. One sits outside the house.
Spending twenty minutes on the checks below can save a detection visit, or at least make that visit faster and more focused.
Common look-alikes
| Look-alike | How to check | Clue it is not the slab |
|---|---|---|
| Running toilet | Add a few drops of food coloring to the tank, wait without flushing | Color appears in the bowl |
| Irrigation valve | Turn off the irrigation supply valve and recheck the meter | Meter stops with irrigation off |
| Yard service line | Close the house main and recheck the meter | Meter still moves with the house main closed |
| Water heater relief valve | Look at the discharge pipe from the relief valve for drips | Water at the end of the discharge pipe |
| Water softener | Check whether it is stuck in a regeneration cycle | Water running to its drain line |
| Pool or fountain auto-fill | Shut off the fill valve and recheck | Meter stops with the fill off |
Work from the outside in
- Confirm the meter moves.Everything off, watch the leak indicator for 15 minutes.
- Close the house main.If the meter still moves, the leak is between the meter and the house, or on an irrigation line fed before the main.
- Isolate outdoor uses.Turn off irrigation, pool fill and any outdoor branch you can isolate, then recheck.
- Check toilets and appliances.Dye test each toilet; check the softener, ice maker line and relief valve discharge.
- Isolate the hot side.Close the water heater's cold inlet; if the meter stops, look under the slab on the hot side.
Example: the wet planter
Illustrative example. Not a real job or customer.
A homeowner's bill jumps and the meter turns with everything inside off. There is no warm floor, but a planter by the front walk stays wet.
- They close the house main; the meter keeps turning.
- They close the irrigation supply valve; the meter still turns.
- That points to the service line between the meter and the house, under the front yard.
- A plumber is called for a yard line repair rather than slab leak detection.
The house slab was never involved. Knowing that before calling changed which repair was discussed. Illustrative example only.
Clues that point under the slab
- Meter stops when the house main is closed but moves when it is open with everything off
- Toilets, irrigation, softener and relief valve all ruled out
- A warm floor, damp flooring away from fixtures, or a hiss under the floor
- Meter stops when the water heater inlet is closed, pointing to the hot side
Common questions
Can a toilet use enough water to look like a slab leak?
A constantly running toilet can waste a lot of water and will turn the meter steadily. It is one of the first things to check.
My meter moves even with the main closed. What now?
The leak is likely between the meter and your shutoff, or on a line that branches off before the main, such as some irrigation setups. A plumber can test the service line.
Do I need a plumber for a toilet flapper?
Many homeowners replace flappers themselves. If you are unsure, a plumber can do it quickly, and it is far cheaper than slab work.
General information for Anaheim Hills, not a quote or professional advice. In an emergency, call 911.