Do your own meter test
Turn everything off
Make sure no faucets, toilets, the washer, dishwasher, ice maker or irrigation are using water.
Find the meter
It is usually in a box near the street or sidewalk. Lift the lid carefully; insects and spiders sometimes live inside.
Watch the indicator
Many meters have a small triangle or dial that spins with any flow. Note its position or the reading.
Wait and compare
Check again after 15 to 30 minutes without using water. Any movement means water is leaving somewhere.
Narrow it down
Close the main house shutoff and recheck. If the meter stops, the leak is inside the house; if it keeps moving, it may be in the line between the meter and the house or in irrigation.
Common hidden leak locations
- Toilet flappers leaking silently into the bowl.
- Irrigation valves or broken sprinkler lines.
- Supply lines under a slab floor.
- Pipes inside walls behind showers and sinks.
- The main line between the meter and the house.
- Water heater relief valve discharging to an outside line.
Tools plumbers use
| Method | How it works | Good for |
|---|---|---|
| Pressure testing | Isolates a line and watches whether it holds pressure | Confirming which line is leaking |
| Acoustic listening | Sensitive microphones pick up the sound of escaping water | Pinpointing leaks under slabs and in walls |
| Thermal imaging | A camera shows temperature differences on surfaces | Hot water leaks and wet areas in walls and floors |
| Moisture meters | Measure moisture in drywall, wood or flooring | Mapping how far water has spread |
| Line tracing | Follows the path of a pipe from above | Finding where a buried or hidden line runs |
| Sewer camera | Video inspection of drain lines | Leaks and breaks in drain and sewer pipes |
Example: a high bill and nothing visible
Illustrative example. Not a real job or customer.
A homeowner in a single-story slab house notices a much higher water bill. No fixtures are dripping and the floors look fine.
- The meter test shows slow movement with all water off.
- Closing the main house shutoff stops the meter, so the leak is inside.
- Food coloring in each toilet tank shows no flapper leaks.
- The plumber closes the water heater's cold inlet and the meter stops, pointing to the hot side.
- Acoustic listening and thermal imaging locate a warm spot under the hallway floor.
The homeowner receives a written explanation of a slab leak on the hot line with two options, spot repair or reroute, before any concrete is opened.
Questions to ask about leak detection
- Which methods will you use, and how precise are they in this situation?
- Is leak detection priced separately from the repair?
- Will you mark the location and explain how confident you are before opening anything?
Common questions
Can a leak be inside the house if I see nothing?
Yes. Water under a slab or inside a wall can drain into soil or cavities for some time before any sign appears.
Is the irrigation system a common cause?
Yes. Underground sprinkler lines and valves leak often and can be checked by shutting the irrigation valve and repeating the meter test.
Does leak detection damage anything?
The methods above are non-invasive. Opening walls or floors only happens once the leak is located and you agree to the repair.
General information for La Palma, not a quote or professional advice. In an emergency, call 911.