To replace a kitchen sink shutoff, turn off the main, drain lines, swap the valve, then test for leaks with dry tissue.
If the stop under your sink is stuck, dripping, or won’t close, a quick swap restores control of the faucet and dishwasher line. This guide shows a clean, safe method that a careful DIYer can follow in a single session. You’ll see the tools, the prep, the exact order of operations, and what to do when things don’t go to plan.
Know Your Stop: Styles, Pipe Types, And Connection Choices
Under-sink shutoffs (often called angle stops) connect the copper, PEX, or CPVC stub-out to flexible supply hoses. The three common attachment styles are compression, threaded (FIP), and push-to-connect. Pick a new valve that matches your pipe and the outlet size your faucet or dishwasher hose expects (most faucets use 3/8-inch compression on the outlet; dishwasher branches often use 3/8-inch or 1/4-inch).
| Valve Style | Works With | Notes |
|---|---|---|
| Compression Angle Stop | Copper or PEX/CPVC with stub adapter | Metal ferrule compresses onto pipe; no thread sealant on the compression threads. |
| Push-To-Connect Stop | Copper, CPVC, or PEX | Slides on to marked insertion depth; removable with a dedicated tool. |
| Threaded (FIP) Stop | Male threaded adapter on stub-out | Use PTFE tape or pipe dope on male threads only; do not over-torque. |
Safety, Water Quality, And When To Pause
Choose drinking-water components labeled “lead-free.” In the United States, “lead free” means a weighted average of 0.25% or less on wetted surfaces, with 0.2% for solder and flux. You can confirm these limits on the U.S. Environmental Protection Agency’s page for the lead-free plumbing rule. If your home has very old brass or questionable fittings, replace them with certified parts rather than reusing.
Pause and call a pro if the stub-out is loose in the wall, the stop feeds a built-in filter or icemaker you can’t isolate, or you see green corrosion around a soldered joint within a few inches of the valve. Movement at the wall can crack a solder or crimp; that repair needs torch work or a press tool.
Tools And Materials
Gather everything before you shut off the supply. Lay a towel and a shallow pan under the cabinet to catch water.
- New shutoff valve (matching pipe type and outlet size)
- Two adjustable wrenches or a wrench plus pliers
- PTFE thread tape or pipe thread sealant (only for threaded male connections)
- Push-to-connect removal clip or tongs (for push-fit valves)
- Tubing cutter (for copper) or a clean, square PEX/CPVC cutter
- Deburring tool or fine file for copper ends
- Rag or tissue, flashlight, and a small bucket
- Optional: compression ring/ferrule puller, spare ferrule and nut
Steps To Replace The Under-Sink Shutoff Valve Safely
1) Isolate, Drain, And Confirm Zero Pressure
Shut the main water valve for the house. Open the kitchen faucet and another lower fixture to bleed pressure. Keep the faucet open during the swap so any trapped water has somewhere to go.
2) Remove The Supply Hose From The Old Stop
Use a wrench on the valve body to hold back while loosening the hose nut with another tool. Set the hose where it won’t drip onto power cords or disposal wiring.
3) Take Off The Old Valve
Compression style: Hold the valve body and loosen the compression nut behind it. The nut and ferrule may stay on the pipe. If the ring is stuck, a ring puller removes it without nicking the copper. Reusing a clean, tight ferrule is common, but if there’s scoring or ovaling, cut the pipe back to fresh material and install a new ring.
Push-to-connect: Slide the manufacturer’s removal tool against the release collar and pull the valve straight off. SharkBite’s guide shows the motion and tool placement for a clean release; see the brand’s instructions on using the push-fit removal tool.
Threaded (FIP): Turn the valve counterclockwise off the male adapter while holding the adapter with a backup wrench at the wall so the stub-out doesn’t twist.
4) Prep The Pipe End
Wipe the stub-out dry. For copper, square the end with a cutter if it’s dented, then deburr inside and out. For PEX or CPVC, make a clean, square cut. Any burrs or oval shapes can prevent a seal.
5) Fit The New Valve
Compression: Slide on the nut and ferrule in that order, push the valve onto the pipe until it bottoms, then finger-tighten the nut. Hold the valve body and tighten the nut a quarter-turn at a time until snug. No thread tape on the compression threads—the seal happens at the ferrule and cone, not the threads.
Push-to-connect: Mark the insertion depth using the brand’s gauge and push the valve straight on until the mark meets the collar. Tug lightly to confirm it latched.
Threaded: Wrap the male adapter’s threads with PTFE tape, 2–3 wraps clockwise as you face the threads, or use a thin coat of thread sealant. Start the valve by hand to avoid cross-threading, then snug with a wrench while holding the adapter with a backup tool.
6) Reconnect The Faucet Hose And Dishwasher Branch
Hand-start the 3/8-inch compression outlet nut to avoid cross-threading, then snug. If your dishwasher tee connects at the stop, attach it before the faucet hose so you can reach the back nut.
7) Restore Water And Check For Leaks
Close the new stop, open the main, then slowly open the stop to the faucet. Use dry tissue around every joint—the ferrule, the push-fit collar, and the outlet nut. The tissue shows even tiny drips. Tighten a compression nut in small steps until the dampness stops. If a push-fit seeps, push the pipe in again to seat or remove and re-cut to a clean end.
Why Stops Fail And What You Can Service Without Full Replacement
Old multi-turn stems wear out, mineral deposits build under seats, and packing dries around the stem. If the body is sound, a stem rebuild kit or a simple packing nut tweak can buy time. Home center guides show this quick repair path if the valve body itself isn’t corroded.
Thread Sealant Rules That Avoid Headaches
Only seal male pipe threads (NPT). Compression connections seal at the ferrule and matching cone inside the valve, not on the threads that you see. Tape on those threads can lubricate the nut in a pinch, but it’s not the seal; rely on a clean pipe, a round ferrule, and measured torque. Keep sealant out of the waterway so debris doesn’t jam a cartridge downstream.
Placement Tip: Handle Direction And Access
Angle stops sit a couple of inches off the wall. Leave enough room for the handle to turn without hitting the cabinet or disposal, and route the faucet hose with a gentle loop so it doesn’t kink when you open and close the stop.
Under-Sink Swap: Time, Cost, And Skill Level
Most replacements take under an hour when the stub-out is sound and the cabinet is clear. The valve is inexpensive, and you may already own the basic hand tools. Add a ferrule puller to your kit if your home has older compression rings that never want to budge.
Common Mistakes To Avoid
- Skipping the main shutoff and trying to “swap fast.” Even a small stream can flood a cabinet.
- Cranking a frozen compression nut without a backup wrench. That twist can crack pipe in the wall.
- Putting PTFE tape on compression sealing surfaces. It doesn’t help, and shreds can foul the valve.
- Failing to deburr or square a cut. A sharp edge can slice an O-ring in a push-fit stop.
- Over-tightening the outlet to the faucet hose. Snug is enough; crushing the ferrule deforms the fit.
Troubleshooting After The Swap
Use this quick map to find and fix drips fast. Keep the water on while you test so you can see where the seep starts.
| Symptom | Likely Cause | Quick Fix |
|---|---|---|
| Drip at compression nut | Ferrule not seated or pipe not round | Tighten 1/8 turn; if it persists, remove, re-round pipe, new ferrule. |
| Drip at push-fit collar | Shallow insertion or burrs | Push to full depth; if needed, remove with tool, re-cut square, deburr. |
| Weeping at threaded joint | Insufficient thread seal or cross-thread | Back off, re-tape or re-dope, hand-start straight, then snug with backup. |
| Handle turns, no shutoff | Stem failure inside valve | Swap the valve; a rebuild won’t restore a broken stem. |
| Dishwasher hose won’t seal | Mismatched outlet size or damaged gasket | Verify outlet spec; replace hose washer or use correct adapter. |
| Hammer or banging sound | Loose pipes or fast close on quarter-turn | Secure lines; crack the stop slightly less during normal use. |
Detailed Walkthrough: Compression Stop Replacement
Measure And Match
Confirm the stub-out diameter (often 1/2-inch copper). Match the outlet to the faucet hose (often 3/8-inch compression). If a dishwasher tee is needed, pick a stop with an integrated branch or add a compact tee at the outlet.
Dry Fit And Orient
Slide nut and ferrule onto the pipe, seat the valve, and set the outlet to face the hose route. Hand-start the nut; threads should spin smoothly.
Tighten With Control
Hold the valve body with one tool and tighten the nut with the other. Stop at resistance, then add small turns until the nut feels firm. Turn on the main, open the stop, and watch the joint. If a drop forms, give it one more small turn. Patience beats brute force.
Detailed Walkthrough: Push-Fit Stop Replacement
Cut Clean, Deburr, And Mark Depth
Use a brand-approved depth gauge and mark the pipe. That mark verifies a full seat. Burrs and scratches near the end can nick the internal O-ring, so smooth them away.
Seat And Test
Push the stop straight on to the mark. Tug gently; it should hold. Open the main and test with tissue. If you need to remove it, use the brand’s clip or pliers to press the release collar evenly while pulling straight back. The manufacturer video for push-to-connect installs shows the exact motion, including depth marking and pipe prep; see push-to-connect stop installation.
Code And Product Labels You Should See
On potable lines, pick components labeled to meet the lead-content limits tied to the Safe Drinking Water Act and certification to NSF/ANSI/CAN standards. The EPA page above explains the threshold and definitions, and many stops list the certification body on the box.
Pro Tips That Save Time
- Keep a ferrule puller on hand. It saves the copper when an old ring refuses to move.
- Use two tools any time you loosen or tighten a joint near the wall. One holds, one turns.
- Mark push-fit insertion depth every time. The line is your instant leak check.
- Replace old supply hoses while you’re in the cabinet. New braided lines cost little and prevent callbacks.
- Cycle the stop once a season so the stem doesn’t seize. Quarter-turn ball stops resist sticking better than old multi-turn styles.
What To Do If The Stub-Out Is Too Short
If a past cut left almost no pipe, you still have paths. A short repair coupling or a push-fit extension can give back the length you need. Keep any torch work far enough from cabinet sides to avoid scorching, and use a heat shield when soldering near wood.
When To Replace The Pair
If one stop fails, the mate on the other sink line is often the same age. Swapping both prevents mismatched operation and saves you from pulling everything out twice.
Cleanup, Final Checks, And Documentation
Dry the cabinet, wipe the valve body, and run the faucet hot and cold. Check again in an hour and the next day for any weeping. Snap a quick photo of the installed stop and keep the receipt in your home folder so you know the model and install date if you need parts later.
Printable Mini Checklist
Copy this rundown to your phone before you start:
- Main off → faucets open → bucket and towel ready.
- Hose off → old stop off with a backup wrench.
- Prep pipe end → square cut → deburr → depth mark if push-fit.
- New stop on (compression, push-fit, or threaded) → orient outlet.
- Hose on → main on → valve open slowly → tissue test every joint.
- Retighten once if needed → recheck in an hour and next day.
Final Word: A Clean Swap Beats A Forced One
Take the time to prep the pipe, back up every joint with a second tool, and test with tissue. With those habits, this cabinet-level repair stays tidy and reliable.