When running a water supply tube to a new refrigerator ice maker, humidifier, or other appliance, you'll need a way to tap into an existing water supply pipe. An easy way to do this on a copper pipe is by using a special fitting known as a saddle valve or needle valve. The term saddle derives from the shape of the valve as it sits atop a water pipe; the term needle refers to the sharp, hollow needle inside the valve that punctures the water pipe after the valve is mounted.
Once the valve is attached to the water supply pipe by means of its saddle bracket, the sharp valve needle is then screwed down to puncture the wall of the pipe and tap its water supply. Most saddle valves are designed to work with standard rigid copper pipes—they are not recommended for PVC, CPVC, or PEX plastic pipe. They are also designed for water systems with a maximum pressure of no more than 125 psi.
What Is Maximum Psi of a System?
Water pressure is measured in pounds per square inch, or psi, using a pressure gauge. Most residential water pressure systems should be between 45 and 80 psi; water pressure above that can damage home plumbing.
Saddle Valves Can Leak
Any plumber or building inspector will tell you that saddle valves are prone to leaking, and it's true. They are popular because they are easy to use and require no plumbing skills to install. Plenty of saddle valves have worked reliably and leak-free for many years, but due to the mixed track record of these devices, it's best to use them only where they are completely visible and can be inspected periodically. Never install a saddle valve where it is concealed inside a wall or floor cavity. Leaks in hidden locations are likely to cause significant damage before they are detected.
Equipment / Tools
- Fine wet/dry sandpaper or steel wool
- Adjustable wrench
- Saddle valve kit
- Water supply tubing
Turn off the Water
Shut off the water supply to the water pipe being tapped. If there is no shutoff valve that can turn off the pipe locally, turn off the water to the entire house at the main shutoff valve. In either case, relieve pressure in the water lines by opening the lowest faucet in the house.
Prepare the Pipe
Make sure the water pipe is clean and smooth along the section where you will be attaching the valve. If necessary, lightly sand the area with fine wet/dry sandpaper or fine steel wool to clean the pipe.
Mount the Valve
Make sure the needle is completely retracted into the saddle valve before starting.
Place the rubber washer or gasket on the underside of the top bracket of the saddle valve so its opening is directly aligned with the needle on the valve. Fit the top and bottom brackets of the saddle valve around the water supply pipe and hold them in place.
Insert the bolts down through the holes on the top bracket and thread them into the holes on the bottom bracket until they are hand-tight.
Use a screwdriver to tighten the bolts completely, alternating side-to-side so the brackets are tightened evenly on both sides of the pipe. The rubber washer under the top bracket should compress slightly against the water pipe.
Be careful not to overtighten; it is possible to crush the copper pipe.
Install the Water Supply Tube
Fit the compression nut and compression sleeve onto the water supply tube so the tapered (narrower) part of the sleeve faces the end of the tube (plastic or nylon tubing may also have a brass insert to stiffen the end of the tubing).
Insert the water supply tube into the threaded outlet on the saddle valve, push the sleeve against the outlet, then screw the compression nut onto the threaded outlet. Tighten the nut by hand until snug, then use an adjustable wrench to tighten the nut another one-half turn.
Pierce the Pipe
Turn the saddle valve handle clockwise slowly. This will force the needle in the valve to pierce the wall of the pipe. You should be able to feel the needle force its way into the copper pipe. Keep turning the handle until it stops.
Turn on the Water
With the saddle valve still in the off position (turned fully clockwise), turn on the water supply to the pipe, then check all around the saddle valve for leaks.
Connect the Supply Tube
Complete the water connection by attaching the opposite end of the water supply tube to the appliance you are feeding.
Open the Saddle Valve
Confirm that all connections are tight. Open the saddle valve fully by turning the handle counterclockwise until it stops. Check again for leaks at all connections.