How to Replace a Stop Valve

Lead Image for How to Replace a Stop Valve
  • 1-2 hours
  • Intermediate
  • 10-40
What You'll Need
Adjustable wrench
Plumbers tape
Stop valve
Slip joint pliers
Small hacksaw

A stop valve is used in plumbing to shut off the supply of water to a specific appliance rather than having to close off the water supply to the entire building. They are found on water plumbing systems such as faucets or anything else which requires a water supply.

After a time, the stop valves tend to wear out and they will need replacing. Fortunately, they are cheap and easy to replace and replacement stop valves can be bought at any hardware store for around $10 or less. Installing a new one takes about 20 minutes even for somebody who is not very experienced with DIY.

Step 1 - Shut off the Main Water Supply

Before starting work, you should switch off the water supply to the building. The main source of the water will not be prevented as you are replacing the stop valve, the purpose of which only applies to the individual appliance.

Step 2 - Remove the Old Stop Valve

Using the adjustable wrench, remove the water supply hose which terminates at the stop valve. Cut the valve off the water line using a keyhole hacksaw. The old valve may be attached using a compression fitting in which case you will find a nut which holds it onto the pipe. Use the pliers to hold it tight while you unscrew the nut. Finally, remove the valve and the ring at the end of the water line. You will probably need to use the slip joint pliers to twist of the compression ring so that you can easily remove the old stop valve.

Step 3 - Prepare for Installing the New Stop Valve

You are now ready to start installing the new valve. Unpack the valve which you purchased earlier and find a new compression ring. Any new stop valve should come with a new compression ring. Slight this onto the water pipe to about a half inch from the end of it.

metal stop valve with plastic switch

Step 4 – Place the New Stop Valve

Unpack the new stop valve and slide it onto the end of the water line. Place the nut onto the thread and you should find that the compression ring will be fixed firmly in place between the fitting on the stop valve and the nut. This will provide a watertight seal provided that you tighten the nut using the wrench. Be sure that the fitting is tight enough, and hold the water line at the same time using the pair of pliers.

Step 5 - Test the Installation

Finally, reconnect the water supply hose. Turn on the mains water supply and test the installation. When you turn on the water supply and start using the appliance, you should find that it works perfectly. If there are any leaks, you should determine where they are coming from and fix the problem accordingly. Be sure that the nut is tight and that you connected the stop valve correctly.