Almost every repair video on this site starts the same way: “First, shut off the water” or “Turn off the breaker.” This guide shows you where those shut-offs are and how to use them, plus the one shut-off we’d rather you left alone.
Do this walk-through now, with a flashlight and a roll of tape to label what you find.
Water
Fixture shut-offs. Most sinks and toilets have a small valve on the supply line, under the sink or behind the toilet. Turn it clockwise to close. Use these for single-fixture jobs like a running toilet, a leaky faucet or a leak under the sink. If one won’t turn or still drips when closed, it needs replacing. Use the main for that job.
The main shut-off. Usually where the water line enters the house: in the basement on the front wall, near the water heater, in a utility room, or in a crawl space. In warm climates it can be outside, near the meter. Utility consumer advocates such as Indiana’s tell homeowners to know where it is, because a burst pipe is the moment you’ll need it.
- A lever (ball) valve is closed when the handle is crosswise to the pipe.
- A round wheel (gate) valve closes clockwise. Old gate valves can stick or break, so turn firmly, not violently.
- After closing the main, open a low faucet to drain pressure from the lines.
The water heater. Most have a cold-water shut-off on the inlet pipe at the top. For a gas water heater, the gas side is a job for a licensed technician.
Power
Find the panel. Usually in the basement, garage or a utility room. Inside the door there should be a directory of which breaker feeds what. If it’s blank or wrong, map it with a helper and a lamp, then label it.
Turn off one circuit. Flip the breaker for the room you’re working in to OFF.
Turn off everything. The main breaker, usually at the top of the panel and often labelled with the service size, shuts off the branch circuits in the house. It doesn’t de-energize the wires coming into the panel from the street. Those stay live.
Then test. A breaker label can be wrong. Before you touch a switch, outlet or fixture, test it with a non-contact voltage tester, and test the tester on a circuit you know is live first.
Don’t work inside the panel. Replacing breakers and anything beyond the cover belongs to a licensed electrician. In Ontario, any electrical work, even small jobs, needs an ESA notification before you begin. See When to call a licensed pro.
Older homes may have a fuse box instead of breakers. Turn off the main switch before removing a fuse, and replace a fuse with the same rating only.
Gas
Know where the meter and appliance valves are. The meter is usually outside or in the basement. Each gas appliance (furnace, water heater, range, dryer) also has its own shut-off valve on the supply pipe nearby.
If you smell gas, utilities add a sulfur-based odorant called mercaptan that smells like rotten eggs:
- Stop what you’re doing and leave the building right away.
- Don’t use light switches, phones, garage door openers or anything that could spark, and don’t start a car in the garage.
- Don’t try to find the leak or shut off gas valves. That’s the Kansas Corporation Commission’s advice, and most utilities say the same.
- Once you’re somewhere safe, call your gas utility or 911.
- Don’t go back in until a gas company employee says it’s safe.
Turning gas back on means relighting pilots and checking every appliance. Leave it to your utility or a licensed gas technician.
Make a shut-off card
On an index card, or a photo on your phone, note:
- where the main water valve is, and which way it closes
- where the panel is, and which breaker is the main
- where the gas meter is, and your gas utility’s emergency number
Tape a copy inside the panel door.