Middlesex Water

Tidewater Utilities, Inc.

How to Locate and Turn Off Main Water Valve in Case of an Emergency

Locating and Operating Your Master Water Valve

Don’t wait until a water emergency to find the location of your master shut off valve. The master valve is probably the most important piece of your internal plumbing system. It controls the flow of water throughout your home. You and everyone in your household should know where it is and be able to locate it in a moment’s notice. In case of an emergency, you cannot afford to waste time searching for the valve. You must be able to locate and operate it immediately. If your property is going to be unoccupied for a long period of time, you might want to consider shutting the valve off to avoid or minimize any water emergencies during your absence. In addition, a plumber can drain your lines if the house will be subjected to below freezing temperatures.


It is important to understand that different plumbing arrangements will dictate where the proper main supply valve is located:

  1. Some homes have the water meter located inside, while others are located outside, underground within a “pit” at or near the property line or rightof-way. Some homes also have submeters, they are typically inside even if the main meter is outside/underground.

  2. Newer homes have fire sprinkler systems, while older ones generally do not.

  3. Home construction also differs greatly; basements, crawl-spaces, and slab-on-grade.

  4. Water shut-off valves may have round “wheel” handles or lever handles.

Locating the proper valve

  1. Basements – the shut-off valve is typically located near the front foundation wall. The main water may have come through the concrete floor or through the wall. The valve is typically within 3-5 feet of where the main water enters. In some cases, the main water may enter in a different area, like a mechanical room, up through the floor, near the water heater or furnace.

  2. Crawl-space plus a basement – the shut-off valve may be where the water enters the basement or in some older homes, the shut-off may be inside the crawl space. If the latter is true, you may want to consider a secondary valve located in the basement.

  3. Crawl-space with no basement – the shut off valve will typically be located near the water heater or under the kitchen sink, but anywhere is possible. As with “B” above, it may be inside the crawl-space; in which case, you may want to consider a secondary valve located up in the living space (near the water heater or under a sink).

  4. Slab-on-grade construction – the shut-off valve will typically be located near the water heater or under the kitchen sink, but anywhere is possible.

Choosing the proper valve to operate

Once you have found the master valve, confirm that it is the correct valve by shutting it off to see if all the water faucets in your home also shut off. If they do not, resume your search.

When you find the right valve, make it more visible by marking it with a brightly colored tag, ribbon or paint so that you, or anyone else, can find it easily during an emergency.

Closing the main valve (Close/Turn-off)

  1. Hand turn the valve (clockwise for gate valves and perpendicular to the pipe for ball valves) or use the appropriate tool depending on the design.

  2. Open a tub or sink faucet (hot & cold) on the highest level to relieve pressure and watch that spout to ensure a full shut-down. Then continue to open faucets throughout the home to drain-down as needed.

  3. If draining down home, be sure to de-energize the water heater and boiler where applicable by shutting off power to electric water heaters and any type of boiler. For gas water heaters, turn thermostat down to the pilot only setting; if you drain the heater, shut off the gas.

WARNING: Old water valves can be damaged and corroded. Only use your hand to turn your water valves on or off. If you cannot do it by hand, call a professional plumber.

Opening the main valve (Open/Turn-on)

  1. Close all faucets except a tub or sink on the highest level.

  2. Partially turn-on valves slowly; extra slow for lever handles; stop after ½ revolution on wheel handle, ½ of a ¼ turn for lever handle; with water flowing, slowly turn-off highest open faucet.

  3. Listen for water pressure to equalize (noise ends); fully open main valve. Bleed air from lines by slowly opening (hot and cold) on all faucets, one at a time, until air stops flowing, then close each faucet; move to all others until complete.

  4. Only turn power on to electric water heaters and boilers after the water system is full and all air has been bled-out. If gas was turned-off, carefully following re-starting direction on the appliance jacket or call a registered plumber or your gas company for service.