How to install a quarter-turn shutoff valve
Replace an old or leaking plumbing angle stop with a new quarter-turn compression shutoff valve on a copper supply line to prevent household water damage.
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🧰 Required Tools & Equipment
- ✓ Two adjustable wrenches
- ✓ Small bucket or shallow catch pan
- ✓ Emery cloth or fine grit sandpaper
- ✓ Ferrule removal tool or tubing cutter
- ✓ Clean rag or microfiber towel
📦 Materials & Supplies
- ✓ 1/2-inch Nom x 3/8-inch OD quarter-turn compression angle stop valve
- ✓ Brass compression ferrule (olive) and nut
- ✓ Drop of silicone plumber's lubricant or paste (optional for threads)
⚠️ Safety Checkpoints & Warnings
- • Verify the home's main water shutoff valve is fully closed before loosening any plumbing connections.
- • Open the lowest faucet in the house to completely drain residual water pressure from the supply lines.
- • Wear safety glasses to protect eyes from residual pipe debris and splashing water.
📋 Step-by-Step Guide (7 Steps)
Shut off main water and drain the line
Turn the main water shutoff valve clockwise until fully closed. Place a catch pan beneath the existing angle stop and open the valve handle along with a nearby faucet to relieve residual water and pressure.
- • Water flow from opened lower fixtures completely stops.
- • Catch pan is positioned directly under the stub-out pipe.
- • Skipping line draining, resulting in sudden water spray when loosening fittings.
Remove old valve and disconnected supply line
Place one adjustable wrench on the valve body to hold it stable and a second wrench on the compression nut behind the valve. Turn the nut counter-clockwise to break it free, then slide the old valve off the copper pipe.
- • Old valve body is completely separated from the copper pipe stub-out.
- • Bare copper pipe end is visible protruding from the wall.
- • Torquing the valve using only one wrench, twisting and damaging the copper pipe inside the wall.
Clear the old ferrule and prep pipe surface
Remove the old brass ferrule and nut using a ferrule puller, or inspect the pipe if reusing a pristine ferrule. Clean the outer copper surface thoroughly with emery cloth until bright and completely free of corrosion, paint, and burrs.
- • At least 1 inch of shiny, bright copper is visible with no ridges or old mineral buildup.
- • Leaving deep gouges in the copper pipe from pliers, which prevents a watertight seal.
Slide on compression nut and ferrule
Slide the new compression nut over the copper pipe with the threads facing outward toward the open pipe end. Slide the brass ferrule onto the pipe directly behind the nut.
- • Nut is on the pipe with internal threads facing toward the pipe end.
- • Brass ferrule ring is seated evenly on the pipe ahead of the nut.
- • Installing the compression nut backwards so threads point toward the wall.
Seat valve body and hand-tighten
Push the new shutoff valve straight onto the copper pipe until the pipe bottoms out fully inside the valve socket. Slide the ferrule and nut forward to engage the valve threads, turning the nut clockwise by hand until snug.
- • Valve outlet is oriented in the desired direction (usually pointing straight up toward fixture).
- • Compression nut is engaged by hand with at least 2 full turns onto the valve body.
- • Cross-threading the brass nut onto the valve body by forcing it with a wrench.
Tighten the compression fitting
Place one adjustable wrench securely across the flat sides of the valve body and the other onto the compression nut. Hold the valve body stationary to maintain orientation while tightening the nut approximately 3/4 to 1 full turn past hand-tight.
- • Valve outlet remains pointed in the correct final orientation.
- • Compression nut shows 1 to 2 exposed threads and is firmly seated.
- • Overtightening the nut, which crushes the copper pipe or distorts the ferrule and causes permanent leaks.
Pressurize system and test for leaks
Ensure the new angle stop valve handle is turned completely off (perpendicular to body). Turn the home's main water valve back on slowly, then dry the connection and inspect the nut joint with a dry tissue for 60 seconds.
- • Tissue pressed around the nut and pipe joint stays completely dry.
- • Valve handle turns smoothly 90 degrees to deliver water to the fixture when opened.
- • Slamming the main water valve open rapidly, causing water hammer in household lines.
Credit: inspired by an original tutorial by MrVex — watch the original on YouTube.
Don’t have everything?
- No Ferrule removal tool? Mini tubing cutter (cut pipe just behind the old ferrule if excess pipe length permits)
- No Emery cloth? 0000 steel wool or 400-grit sandpaper