The situation
Illustrative example. Not a real job or customer.
An owner of an older slab home hears from a neighbor about a slab leak down the street and notices their own meter indicator moving with everything off. They assume the worst.
- They close the house shutoff, expecting the meter to stop.
- The indicator keeps moving.
- They close the irrigation valve as well; it still moves.
- Walking the front yard, they notice a strip of lawn between the meter and the house that stays soft and green during a dry spell.
The evidence points to the service line between the meter and the house, not to the slab.
How the test separated the possibilities
- IfThe meter had stopped with the house shutoff closedThenThe leak would be inside the house, possibly under the slab.
- IfThe meter stopped only when irrigation was closedThenThe leak would be on the irrigation branch.
- IfThe meter kept moving with both closedThenThe leak is on the service line between the meter and the house shutoff, which is what happened here.
What happened next
- Check the boundary.Because the leak might be near the meter, the owner asks the City of Fullerton's water utility which side of the meter is theirs.
- Call 811.Before any digging, underground utilities are marked.
- Locate.A licensed plumber confirms the leak on the owner's side of the service line and narrows its position.
- Choose a fix.The plumber explains repairing the section versus replacing the whole service line, and whether a trenchless approach suits the yard.
- Test.After the repair, the owner's meter test shows no movement with everything off.
What a slab leak repair would have meant instead
Service line repair (actual)
- Work in the yard
- No floors or walls opened
- Landscaping restored afterward
Slab leak repair (avoided)
- Concrete or walls opened inside
- Flooring or drywall restoration
- Disruption inside the house
The lesson
A moving meter tells you water is leaving the system, not where. The house shutoff test takes a couple of minutes and splits the problem in half. Owners who run it before calling give the plumber a head start and avoid assuming the leak is under the floor.
Common questions
Is this a real case?
No. It is an invented example.
What if my house shutoff does not close fully?
The test will not be reliable. Tell the plumber, who may recommend replacing the valve.
Who owns the line at the meter?
Ask the City of Fullerton's water utility where the boundary is for your property.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.