How to Replace a Shut-Off Valve
Updated February 20, 2026
Swap a stuck, leaking, or unreliable shut-off valve for a modern quarter-turn ball valve -- compression, threaded, and push-fit connections all covered.
Overview
Every sink, toilet, and washing machine has a shut-off valve so you can kill the water to that fixture without turning off the whole house. When they fail -- leaking from the stem, seized open, or not closing fully -- they need replacing. The old multi-turn gate valves that were standard for decades are being phased out for quarter-turn ball valves: more reliable, easier to use, and far less likely to seize. How you replace depends on the connection type: compression (most common), threaded, or soldered. This guide covers all three.
What You'll Need
Safety First
- Main water supply off before you touch the old valve. It is the only thing between a pressurized pipe and an open end. Open a faucet on the same floor to drain residual water.
- Bucket and towels ready. Even with the main off and lines drained, water will come out when you disconnect. In basements and crawl spaces, check that water will not drip onto electrical components.
- Compression fittings on copper: do not overtighten the nut. Copper is soft and the ferrule deforms if you crank it, creating a leak you cannot fix without cutting the pipe. Hand-tight plus one full turn is typically enough.
Step-by-Step Instructions
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Turn Off the Main Water Supply and Drain the Lines
Close the main shut-off completely. Open a faucet on the same floor to drain water and release pressure. Bucket and towels under the valve. Disconnect the supply line (the flex hose to the fixture) by unscrewing the nut at the valve end. Let residual water drain. Now you can see how the valve connects to the supply pipe from the wall or floor.
Tip: Replacing a toilet valve? Flush the toilet after killing the main to empty the tank. Less water to deal with when you disconnect. -
Identify the Connection Type and Remove the Old Valve
Look at how the old valve connects to the pipe. Compression (most common): nut and a small brass ferrule where the pipe enters the body. Hold the pipe with one wrench, turn the compression nut counterclockwise with another. Slide the valve off. Ferrule might stay on the pipe -- that is fine. Threaded: two wrenches (hold the pipe, turn the valve), counterclockwise. Soldered: cut the pipe below the valve with a pipe cutter, leaving at least 1 inch of clean pipe extending from the wall.
Warning: Always use a backup wrench on the pipe when removing a compression valve. Without one, the torque can damage the pipe connection inside the wall. That turns a 30-minute job into a major project. -
Prepare the Pipe for the New Valve
Compression: old ferrule still on the pipe? Two options. Easiest: leave it and use a new valve designed to fit over the existing ferrule (many are). Or: slide the old ferrule off (gentle twisting and pulling, or pry carefully with a flathead). Clean the pipe with emery cloth -- smooth, round, and shiny. Threaded: wire brush the threads, inspect for damage. Cut pipe from a soldered removal: deburr the end and sand smooth.
Tip: Ferrule stuck and will not come off? Do not force it. Either use a valve designed for existing ferrules or go push-fit (SharkBite-style) -- slides directly onto the pipe regardless of ferrule situation. Costs $5-10 more but eliminates all ferrule headaches. -
Install the New Quarter-Turn Ball Valve
Compression: slide nut onto pipe (threads facing valve), then ferrule (if old one was removed). Push the valve on until the pipe bottoms out inside the body. Slide nut and ferrule up, hand-tighten, then one full turn with a wrench. Backup wrench on the valve body. Threaded: 4-5 wraps of Teflon tape (clockwise), screw on, 1-2 turns past hand-tight. Push-fit: mark insertion depth on the pipe, clean it, push the valve on until it clicks.
Tip: Match inlet size to your supply pipe (1/2 or 3/8 inch) and outlet size to your supply line (typically 3/8 compression for sinks and toilets). Pipe from the wall? Angle stop. Pipe from the floor? Straight stop. -
Reconnect the Supply Line and Test
Reconnect the supply line to the new valve outlet. Hand-tighten plus a quarter turn -- the washer inside the nut makes the seal, not brute force. New valve in closed position (handle perpendicular to pipe). Turn the main back on slowly, check for leaks at the main. Then open the new valve slowly and check every connection: inlet, outlet, valve body. Any drip? Tighten 1/8 turn at a time. Run the fixture 2-3 minutes and check again.
Tip: While the supply line is off, look at it. Old chrome or plastic line? Replace it with braided stainless steel ($5-10). Old supply lines are the number one source of under-sink and behind-toilet water damage.
Pro Tips
- Always upgrade to a quarter-turn ball valve. Lever handle makes it obvious: in line with pipe = open, perpendicular = closed. Ball valves are far more reliable than gate or globe valves and rarely seize even after years sitting idle.
- Push-fit (SharkBite-style) valves are the easiest install and work on copper, PEX, and CPVC. Cost $5-10 more but eliminate ferrule headaches entirely. Especially useful when the old ferrule is stuck.
- Replace the supply line while you are at it. Braided stainless steel, $5-10. Measure from valve to fixture before buying -- too short is a problem, too long just makes a gentle loop.
- Exercise the new valve once a year -- close fully, open fully. Keeps the ball and seals in good shape and ensures it works when you actually need it in an emergency.
- Kitchen sink with a disposal? Consider a dual-outlet valve (one inlet, two outlets) to feed both the faucet and the dishwasher connection. Simplifies everything under the sink.
When to Call a Pro
Call a plumber if the pipe is galvanized steel and you are worried about cracking corroded threads, if it is soldered copper and you are not comfortable cutting pipe, if the main shut-off does not work (you cannot turn off the water), or if the pipe behind the wall needs extending or repair before a new valve will fit.