Why map your shutoffs now
Every hidden leak test on this site depends on closing the right valve at the right time: the house main to separate inside from outside, the water heater inlet to check the hot side, the irrigation supply to rule out the yard. If you already know where each valve is and whether it turns, those tests take minutes.
Mapping also uncovers problems early. Old gate valves in many Fullerton homes stiffen or stop sealing after years of hard water. Finding a stuck valve on a calm afternoon is far better than finding it with water on the floor.
Worksheet: where each shutoff is
| Shutoff | Where to look | Your location notes | Turns freely? (Y/N) |
|---|---|---|---|
| City water meter | Concrete box near the street or sidewalk | ||
| House main valve | Where the line enters the house, often near a front hose bib or garage | ||
| Water heater cold inlet | Pipe on top of the tank or entering a tankless unit | ||
| Irrigation supply | Near the backflow device or valve manifold | ||
| Kitchen sink | Under the sink, hot and cold | ||
| Each bathroom sink | Under the sink, hot and cold | ||
| Each toilet | Wall or floor behind the toilet | ||
| Washing machine | Hose valves behind the washer | ||
| Ice maker or fridge line | Under the sink, behind the fridge or in the garage | ||
| Water softener or filter | Bypass valve at the unit |
How to walk the house
- Start outside.Find the meter box and note its location. Do not adjust the city's valve inside it.
- Find the main.Trace the line from the street toward the house and look for a valve at the wall or in the garage.
- Go to the water heater.Identify the cold inlet valve and label it.
- Room by room.Open each sink cabinet and look behind each toilet and appliance.
- Label and photograph.Tag valves with a marker or tag and keep photos on your phone.
Keep near the main shutoff
- A copy of this completed worksheet.
- A meter key or long screwdriver for the meter box lid.
- A flashlight.
- Work gloves.
- The gas shutoff location noted separately, with a reminder: if you smell gas, leave and call 911 or SoCalGas from outside.
Valve types you may find
- Gate valve
- Round wheel handle, many turns; common in older homes
- Ball valve
- Lever, quarter turn; closed when lever is across the pipe
- Angle stop
- Small valve at sinks and toilets
- Hose valves
- Behind the washer
Common questions
I cannot find a house main valve. What now?
Some homes have one in an unexpected spot or none at all. In an emergency, the city meter box may have a valve, but contact the city's water utility about operating it, and ask a plumber about adding a house valve.
Should I test every valve by closing it?
Gently operating valves you can turn easily is useful. Leave stiff ones alone and note them for a plumber.
Does everyone in the house need to know this?
Yes. Show every adult where the main shutoff is and how it closes.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.