How to Repair an Interior Main Water Shut off Valve

Shut off valves are an important part of a plumbing system and can save a home from a significant amount of damage if used at the right time. However, valves can leak, break, or become stuck over time and may need to be repaired or replaced for them to remain in good working order. While these valves can often be repaired with a pair of pliers or some WD-40, replacing a valve may be the only option if the valve is too far gone.

Valves are found throughout the home, typically at every toilet, sink, and other plumbing appliance. These smaller shut offs are used to turn off water in one specific area, making for easier access for repairs or to prevent damage in a localized area. The main shut off is a larger valve often found in the garage or in a closet. This valve (often a ball valve) turns off water to the entire home and can also be found at the water meter. If your home has a gate valve at the main water shut off, be careful as these can break and replacing these with a ball valve is recommended.

If a main water shut off valve needs to be replaced, first test the water shut off valve at the street, this is typically found inside the water meter vault at the curb. Since this valve is likely old, it may be a gate valve which can become clogged with mineral deposits and grit. This makes a gate valve almost impossible to close all of the way. If this is the case, call your local water utility for replacing this shut off.

If you are able to shut off the water at the curb, you can proceed in replacing the interior main water shut off valve. Loosen the coupling nut and remove the nipple from the old valve. If you are replacing an older valve, this is a good time to upgrade from a gate valve to a ball valve. Screw in the new ball valve and install the nipple with a new leather washer. Neoprene washers can also be used, however neoprene can eventually dry out and crack. You can use pipe dope or Teflon tape on the threads to ensure a tight installation. Lastly, tighten the coupling nut and turn on the water to test for leaks.