One meter test tells you whether water moved during that hour. Several tests on different days, written down with times and conditions, show a pattern: a steady loss, a loss that only appears when irrigation is on, or a loss that disappears when the house valve is closed. That pattern is what helps separate an interior leak from one on the buried service line between the meter and the house.
Test log
| Date | Time | Condition | Meter reading | Leak indicator moving? | Notes |
|---|---|---|---|---|---|
| All fixtures and irrigation off | |||||
| After 30-60 minutes, still off | |||||
| House main shutoff closed | |||||
| After waiting, house valve closed | |||||
| Toilet supply stops closed | |||||
| Irrigation supply isolated |
Logging routine
- Choose a quiet window.Late evening or early morning works when no one needs water.
- Record the start.Write the full meter number and whether the small leak indicator is turning.
- Wait and record again.Do not use any water. Note the second reading and time.
- Isolate the house.Close the house main shutoff and repeat the wait and reading.
- Repeat on another day.Run the test again within a week to confirm the result.
What your log may be telling you
- IfNo movement on any testThenNo active leak was detected during those windows.
- IfMovement stops when the house valve closesThenThe loss is likely inside the house.
- IfMovement continues with the house valve closedThenThe loss is likely on the service line or a connection before the house valve.
- IfMovement only when irrigation supply is openThenCheck the irrigation system and its valves.
Meter terms
- Leak indicator
- A small dial, triangle or star on the meter face that turns with even very low flow.
- Register
- The numeric display that records total water used.
- Sweep hand
- A large pointer on some meters that shows smaller units of use.
Common questions
How long should each wait be?
Thirty minutes often shows a steady leak. An hour or overnight with no use catches slower ones.
My meter is hard to read. What now?
Wipe the glass, use a flashlight and take a photo. If it is damaged or unreadable, contact the City of Fullerton's water utility.
Should I share the log with the city?
If the leak appears to be on the meter or street side, sharing your readings can help the city check it.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.