Replacing Shutoff Valves
Updated February 20, 2026
Those old multi-turn gate valves under your sink are a ticking time bomb. We see it all the time -- someone goes to shut off the water for a faucet repair, the valve won't close, and now they've got a bigger problem. Swapping to quarter-turn ball valves is cheap, straightforward, and means the next time you need to shut off water, the valve actually works.
Overview
Those old multi-turn gate valves under your sink are a ticking time bomb. We see it all the time -- someone goes to shut off the water for a faucet repair, the valve won't close, and now they've got a bigger problem. Swapping to quarter-turn ball valves is cheap, straightforward, and means the next time you need to shut off water, the valve actually works.
What to Know
Tools & Materials
- Two adjustable wrenches
- Mini tube cutter (for tight spaces)
- Bucket and towels
- New quarter-turn ball valve
- Thread seal tape
Step by Step
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Shut off the main water supply
You're replacing the shutoff, so the local valve can't help. Turn off the main. Open a faucet on a lower floor to drain pressure. Have towels ready.
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Remove the old valve
Disconnect the supply line from the top. Remove valve from supply pipe. For compression, hold pipe with one wrench and turn valve nut with the other. For soldered, cut the pipe below with a tube cutter.
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Prep the pipe
Make sure the cut is clean and square. Remove any old ferrule -- sometimes requires a pulling tool. Clean the pipe end with emery cloth until bright and smooth.
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Install the new valve
Slide compression nut and new ferrule onto pipe. Thread valve body on, hand-tighten, then hold valve with one wrench and tighten nut with the other -- one full turn past hand-tight.
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Reconnect and test
Attach supply line to new valve. Turn main back on slowly. Open new valve. Check compression fitting and supply connection for leaks.
Pro Tips
- A mini tube cutter ($8-$12) is essential for tight under-sink spaces.
- If the old ferrule is stuck, cut the pipe below it and start fresh.
- Replace shutoff valves in pairs -- if one is old, the other is just as bad.
Mistakes to Avoid
- Not turning off the main water first.
- Overtightening the compression fitting -- one turn past hand-tight, that's it.
- Reusing old compression ferrules -- always use new ones.
- Buying the wrong valve size -- measure the pipe outer diameter first.
When to Call a Pro
If the supply pipe is galvanized steel, corroded beyond repair, or if the main water shutoff won't close fully -- call a plumber. Working with live pressure is not DIY territory.
Bottom Line
A $10-$15 per valve project that takes 30 minutes each. Preventive maintenance that pays off the first time you need to shut off water in an emergency.