Before you start
The meter sits in a box near the curb and belongs to the city's water system. You only need to open the lid and read it; do not touch the valve inside. Many meters have a small triangle or dial called a low-flow indicator that spins when any water at all is moving.
Pick a time when nobody needs water for a while, and make sure irrigation timers, the ice maker and any water softener regeneration are not running.
Running the test
Turn everything off
No taps, toilets, washer, dishwasher or sprinklers in use.
Watch the low-flow indicator
If it moves at all with nothing running, water is going somewhere.
Record a starting reading
Write down the full number on the register and the time.
Wait without using water
Leave it for a while, then record the reading again.
Isolate the hot side
Close the cold inlet valve on the water heater and watch the meter. If movement stops, the leak is likely on the hot side.
Isolate the house
Close the main house shutoff. If the meter still moves, the leak may be between the meter and the house or in irrigation lines.
Your readings
| Step | Time | Meter reading | Indicator moving? |
|---|---|---|---|
| Everything off, start | ____ | ____ | Yes / No |
| Everything off, end | ____ | ____ | Yes / No |
| Heater cold inlet closed | ____ | ____ | Yes / No |
| Main house shutoff closed | ____ | ____ | Yes / No |
Reading the results
- IfNothing moves at any stepNo significant leak is showing right now. Check again if bills or symptoms change.
- IfMovement stops when the heater inlet is closedSuspect a hot-water line, possibly under the slab. Ask a plumber about leak detection.
- IfMovement stops only when the main is closedThe leak is inside the house on the cold side, or a toilet is running. Check toilets first.
- IfMovement continues with the main closedThe leak may be on the service line or irrigation. If water is near the meter, contact the city's water utility.
Common questions
Can I open the meter box?
You can usually lift the lid to read the meter. Leave the valve and the meter itself alone; they are the city's equipment.
The meter barely moved. Is that a leak?
Even small, steady movement means water is escaping. A slow leak can still damage a slab or wall over time.
Should I share these readings with a plumber?
Yes. They help a plumber decide where to start looking.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.