Most residential water meters in Fullerton sit in a box near the street or sidewalk. Under the lid you will usually find a dial or digital display showing total use, plus a small leak indicator: often a little triangle, star or wheel that spins whenever water flows, even a trickle.
The test takes about fifteen minutes and costs nothing. Do it before you call a plumber, because the result shapes the whole conversation.
Test 1: is water leaving the system?
- Turn everything off.Close every faucet and shower, make sure no toilet is refilling, and pause the dishwasher, washing machine, ice maker, water softener regeneration and all irrigation timers.
- Wait a few minutes.Give toilets and appliances time to finish filling so they do not move the meter.
- Watch the leak indicator.Look at the indicator for at least two or three minutes. Any steady movement means water is flowing somewhere.
- Take a reading.Photograph the full meter reading and note the time. If the indicator barely creeps, wait thirty to sixty minutes with nothing in use and photograph it again.
- Compare.If the reading changed while nothing was on, you have a leak somewhere on your side of the meter.
Test 2: inside or outside the house?
If test 1 shows a leak, this narrows down where.
- Close the house shutoff.Close the main shutoff where the line enters the house, usually on an exterior wall, often near a hose bib or in the garage.
- Watch the indicator again.If the indicator stops, the leak is inside the house, which includes lines under the slab.
- If it keeps moving.The leak is between the meter and the house shutoff, or in an irrigation line that branches off before the house valve.
Test 3: hot side or cold side?
- Reopen the house shutoff.Leave all fixtures off.
- Close the water heater's cold inlet.The cold inlet is the valve on the pipe feeding into the top of the tank or tankless unit. Leave the gas controls and burner alone.
- Watch the indicator.If it stops, the leak is likely on the hot-water side. If it keeps moving, look at the cold side and the toilets.
What each result usually means
| Result | Likely meaning | Sensible next step |
|---|---|---|
| Indicator still in test 1 | No continuous leak at this moment | Repeat on another day; check irrigation schedules and toilets. |
| Moves, stops with house shutoff closed | Leak inside the house | Check toilets and fixtures, then arrange leak location. |
| Moves even with house shutoff closed | Leak outside, before the house | Look for wet ground along the line; see the service line guide. |
| Stops when heater cold inlet closed | Probably a hot-side leak | Leave the inlet closed except when hot water is needed, and arrange leak location. |
Common questions
My meter has no leak indicator. What now?
Use the full reading instead: photograph it, use no water for an hour, and photograph it again. Any change suggests a leak.
Can a running toilet make the meter move?
Yes. A flapper that leaks into the bowl is one of the most common reasons the indicator moves. Rule out every toilet before assuming a slab leak.
Is it safe to leave the water heater's cold inlet closed?
It stops refilling the heater, so you will run out of hot water. Many owners close it overnight or when away and open it when they need hot water. Ask a plumber if you are unsure about your unit.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.