Why the meter is your best first clue
A buried service line can lose water for months without a puddle you can see. The meter, though, records every gallon that passes through it. If nothing in the house is using water and the meter still moves, something is leaking: a toilet, an irrigation valve, a water heater relief valve, a pipe inside the walls or the line under the yard.
The test does not tell you where the leak is. It tells you whether there is one, and with a second step it can show whether the loss is inside the house or on the buried line.
Running the test
Pick a time when nobody needs water for an hour, such as late evening.
- Turn everything off.Close all faucets and showers, wait for the dishwasher, washer and ice maker to finish, and switch the irrigation controller to off.
- Read the meter.Open the meter box and note the full reading. Watch the small leak indicator (often a triangle or star) for a full minute.
- Wait without using water.Leave everything off for 30 to 60 minutes. Do not flush or run a tap.
- Read it again.Compare the reading. Any change, or an indicator that kept turning, means water is being used somewhere.
- Close the house shutoff and repeat.If the meter moved, close the house main shutoff and watch the indicator again. If it still moves, the leak is likely between the meter and the house.
- Write it all down.Record the times, readings, and whether the indicator moved with the house valve open and closed.
Reading the results
- IfThe meter did not move at allThenThere is probably no active leak at the moment. If your bill is high, look at irrigation schedules and usage first.
- IfThe meter moved, but stopped when the house shutoff was closedThenThe leak is likely inside the house: check toilets, the water heater and fixtures, or ask a plumber to test interior piping.
- IfThe meter kept moving with the house shutoff closedThenThe leak is likely on the buried service line or at an irrigation connection before the house valve. Have the line checked.
- IfThe indicator only moves now and thenThenA toilet refilling or an irrigation valve weeping can cause this. Repeat the test with toilet supply stops closed.
Simple test log
| Step | Time | Reading | Indicator moving? |
|---|---|---|---|
| Start, all fixtures off | |||
| After waiting | |||
| House shutoff closed | |||
| After waiting, valve closed |
Bring these answers to a plumber
- Did the meter move with every fixture and the irrigation off?
- Did it keep moving with the house main shutoff closed?
- Roughly how fast was the indicator turning?
- Has your water bill changed recently?
- Is there any wet or sunken ground between the meter and the house?
Common questions
How long should I wait between readings?
Thirty minutes is often enough to show a steady leak. For a very slow leak, an hour or an overnight test with no water use gives a clearer result.
Can irrigation make the test misleading?
Yes. A weeping sprinkler valve or a broken irrigation line can move the meter. Turning the controller off helps, and a plumber can isolate the irrigation supply if needed.
Does a passed test mean my line is fine?
It means no leak was active during the test. Pressure loss, rusty water or old galvanized pipe can still be reasons to have the line inspected.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.