How To Replace a Shut-Off Valve Under a Sink

How to Replace the Shut-Off Valve Under a Sink.

If you’re like most homeowners, you’ve probably experienced at least one time when a shut-off valve under your sink stopped working. You might have gone through the hassle of trying to fix it yourself or calling a plumber, only to find out that the cost of repair was too high.

Fortunately, there’s an easy and affordable solution to this problem – replacing your shut-off valve with a mechanical one.

Replacing a shut-off valve under your sink may seem like a daunting task, but it’s actually quite simple. In this article, we’ll walk you through the entire replacement procedure.

Required Tools and Materials:

  • Tape measure
  • Pipe wrench
  • Screwdriver
  • Hammer
  • Circular saw or jigsaw
  • Pipe cutter or hacksaw
  • Ruler or straight edge
  • Chisels or saw blades as needed (optional)

Shut-Off Valve Location

If your sink’s shut-off valve is located under the sink, it’s important to replace the valve if it begins to leak. Replacing a shut-off valve can be tricky, so be sure to follow these instructions carefully.

To replace a shut-off valve under your sink, first remove the old valve by unscrewing the stem from the spindle. If the stem is threaded, unscrew it in either direction until it comes free. Then remove the cartridge by gently pulling it out of the spindle.

If your sink has a mounting bracket, position the new cartridge on the bracket and screw it in place. If your sink doesn’t have a mounting bracket, simply slide the cartridge into the spindle. Tighten the screws that hold the cartridge in place.

Replace the stem by screwing it on from below. Replace the cartridge by screwing it on from above. Turn on the water and test to make sure that the valve works properly.

However, Below is the step by step procedure to replace a shut-off valve under a sink.

How To Replace a Shut-Off Valve Under a Sink

Step 1

Turn the water supply off to the stop valve by closing the main gate valve. This main valve is usually located on the exterior of the house.

Step 2

Open the sink’s faucets to drain water from the fixture and release siphon pressure in the water line.

Step 3

Position a bucket or container beneath the stop valve being replaced to capture the small amount of water in the lines when the water line from the faucet is disconnected.

Step 4

Use an adjustable wrench to loosen the small hex nut that connects the water line to the sink faucet.

Step 5

Loosen the larger hex nut at the base of the stop valve, turning it clockwise until it is free of the valve’s threads.

Step 6

Remove the stop valve from the copper water line by pulling it forward. Remove the brass compression ring around the copper water line to free the large hex-head nut.

Step 7

Clean any corrosion or mineral buildup from the exposed copper water line with a piece of emery cloth.

Step 8

Push the new stop valve’s large hex nut onto the copper waterline, with the opening toward you, then slide the new brass compression ring over the copper waterline.

Step 9

Wrap two or three full layers of Teflon thread tape clockwise around the threaded sections of both the large and small hex nut connections.

Step 10

Slip the new stop valve onto the copper waterline and tighten the large hex nut to finger-tight, making certain the water line connection is positioned straight up. Use the adjustable wrench to tighten the hex nut.

Step 11

Connect the waterline from the sink faucet to the smaller connection hole and tighten the hex nut.

Step 12

Turn the control knob on the new stop valve counterclockwise to the fully open position. Open the sink’s faucet.

Step 13

Open the main gate valve to turn the house water supply back on.

Step 14

Check the new stop valve’s connections for leaking, and tighten the hex nut connections as necessary. Do not over-tighten.


If you have a shut-off valve under your sink, it’s important to know how to replace it. Shut-off valves protect water lines from becoming plugged and create an emergency backup in the event that the faucet becomes blocked.

In order to replace a shut-off valve, follow these simple steps:

  • 1) Turn off the main water line to the house by flipping the main switch.
  • 2) Remove the cover on top of the valve box by shifting it towards you and then pulling it off toward the front of the house.
  • 3) Locate and remove the old valve by unscrewing it from its mountings. Save any screws or bolts involved for use later.
  • 4) Install a new valve by screwing it onto its mountings in reverse order, being sure to snug everything down once it is in place. Replace any screws or bolts saved from before.

If you have any questions or run into any problems along the way, be sure to stop by our forum for assistance. Thanks for reading!

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