Shutoffs and Valves

Find it first

The time to find the main shutoff is before a pipe bursts. Walk the house, find every valve below, open and close each one, and tag the main.

The valves a house needs

Wisconsin’s plumbing code sets where control valves go in a one- or two-family house ¹:

1. Curb stop. On city water, a valve in the service line between the water main and the property line. The homeowner’s side starts after it.
2. Building control valve. Inside the house, within 3 feet of where the water service first enters, and upstream of the meter if there is one. On a well with an indoor pressure tank, it’s within 3 feet downstream of the pressure tank. This is the main shutoff. If there’s a meter, a second valve goes within 3 feet downstream of it, so the meter can be changed without draining the house.
3. Water heater and treatment devices. A valve in the supply to each water heater and each water softener or treatment device.
4. Toilets, appliances, and equipment. A stop at each toilet and at each appliance and piece of equipment.
5. Outdoor hose bibbs. A valve for each exterior hose bibb.

All control valves and fixture stops must be accessible, and the valves for fixtures and appliances in a dwelling unit must be reachable from inside that unit ¹. A valve behind drywall doesn’t count.

Kinds of valves

• Ball valve. A ball with a hole through it turns a quarter turn. The lever shows at a glance whether it’s open (in line with the pipe) or closed (across it), and open, it doesn’t restrict flow.
• Gate valve. A round handle that takes many turns to raise or lower a gate. Common on older mains.
• Stop valve (globe pattern). Multi-turn, with a washer that closes on a seat; the typical small valve under sinks and toilets.

Old multi-turn valves left untouched for years can be hard to close or may not seal, which is one more reason to exercise them before an emergency.

Outdoors

A hose bibb or wall hydrant through the wall of a heated building must be frost-proof and self-draining: the valve seat sits deep inside the warm wall, and the part in the cold wall drains when it’s shut off ¹. Disconnect hoses in fall so the bibb can drain.

Any outlet with hose threads counts as a high-hazard cross connection in Wisconsin, because a hose can lie in a bucket of chemicals or a puddle and siphon back into the drinking water; it needs a listed backflow preventer such as a vacuum breaker, one that doesn’t stop the bibb from draining ¹.

Expansion and hammer

Water expands when heated. In an open system, the extra volume pushes back into the city main. Once a check valve, backflow preventer, or other one-way device makes the system closed, that expansion raises the pressure in the house every time the heater runs. Wisconsin requires any storage water heater on a closed system to have an expansion tank or similar device ¹.

When a valve slams shut, the moving column of water stops all at once and the pressure spikes, which you hear as water hammer; spikes can reach 300 to 400 psi in rigid pipe ². Wisconsin requires water hammer arrestors at fixtures and appliances with quick-closing solenoid valves (washing machines, dishwashers) on 3/8-inch or larger inlets, installed in the fixture supply and kept accessible ¹.

What to take from this

Know the five shutoffs: the curb stop, the building control valve within 3 feet of where the service enters (or after the pressure tank on a well), the water heater valve, stops at each toilet and appliance, and a valve for each hose bibb, all accessible from inside. Ball valves show open or closed at a glance; exercise the old multi-turn ones. Outdoor bibbs must be frost-proof, self-draining, and protected from backflow; closed systems need an expansion tank at the heater; quick-closing valves need hammer arrestors.