How to Replace a Shower Valve
Updated February 20, 2026
Replace a shower valve cartridge or the entire valve body to fix temperature swings, stop leaks, or deal with a shower that will not turn off -- single-handle and two-handle valves covered.
Overview
This is one of the more advanced DIY plumbing projects, but manageable if you are confident with tools. Two levels here: replacing the cartridge inside the existing valve body (moderate, 30-60 minutes, no wall access) or replacing the entire valve body (hard, 2-4 hours, wall access and pipe work). Most problems -- dripping, temperature swings, stiff handle, shower that will not fully shut off -- are fixed by a cartridge swap alone. Full valve body replacement is only needed when the body itself is corroded, cracked, or you are upgrading from two-handle to single-handle pressure-balancing.
What You'll Need
Safety First
- Shut off the main water supply -- most showers do not have individual shut-offs. Open the shower valve afterward to drain pressure from the lines.
- Replacing the full valve body means working with copper or PEX inside the wall. Soldering copper in a wall cavity requires a flame protector cloth behind the pipe. PEX with SharkBite fittings is the safer DIY route.
- Pressure-balancing and thermostatic valves have anti-scald protection in the cartridge. Use only the manufacturer's specified replacement. A generic cartridge may not provide anti-scald protection -- that is a serious burn hazard.
- Wall cavities can hide electrical wires, nails, and insulation. Flashlight in first, hands in second. If you find wiring, do not proceed without killing the relevant breaker.
Step-by-Step Instructions
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Determine If You Need a Cartridge or Full Valve Replacement
Dripping, temperature problems, stiff handle? Cartridge replacement fixes that 90% of the time. The valve body itself is usually fine -- it is the internal cartridge that wears out. You only need a full body replacement if: the body is visibly corroded or cracked, it is leaking from pipe connections (not the cartridge area), or you are upgrading valve types. Start with a cartridge swap. Full valve only if that does not solve it.
Tip: Just doing a cartridge? Our dripping shower head guide covers that process in detail. This guide focuses on full valve body replacement for those who need it. -
Access the Valve Body
You need access to the pipe connections behind the wall. Check for an access panel on the other side of the shower wall (adjacent room or closet). No panel? Cut an opening in the drywall on the back side -- stud finder for the studs, mark a rectangle at least 14x14 inches centered on the valve. Cut carefully with a utility knife or oscillating tool. You can patch it later with a drywall access panel ($10-15).
Tip: Always go in from the back side of the wall, never the shower side. Cutting tile or surround material is destructive and expensive to repair. Exterior wall with no back access? That is when you call a plumber. -
Remove the Old Valve
From the shower side: remove handle, escutcheon plate, trim. From the access side: you will see the valve body with hot and cold supply pipes plus outlet pipes to the shower head and tub spout. Main water off, valve open to drain. Soldered copper: pipe cutter or hacksaw, cut about 2 inches from the body. Threaded: unscrew. PEX: cut. Remove mounting screws or brackets, pull the old valve out through the access opening.
Warning: Leave enough pipe length for new connections. Cut too close and you cannot attach the new valve. At least 2 inches of pipe extending from the framing. Measure twice. -
Install the New Valve Body
Position the new valve in the cavity at the correct depth -- most valves have markings for different wall thicknesses so the escutcheon sits flush. Secure to framing with the mounting bracket or screws. Level, correct handle orientation. Connect supply pipes: solder or SharkBite for copper, crimp rings or SharkBite for PEX. Connect outlet pipes to shower head port and tub spout port.
Tip: SharkBite push-fit fittings are the easiest option and work on both copper and PEX. No soldering, no crimping tools -- just push onto the pipe. $5-8 per fitting and they keep you from using a torch inside a wall cavity. -
Test for Leaks Before Closing the Wall
Before closing the wall, turn the main back on slowly and check every connection for leaks. Let pressure build for 5 minutes, flashlight on every joint. Even a tiny drip will cause major damage inside a wall over time. Open the valve from the shower side -- verify water flows through the head and tub spout. Confirm hot and cold are correct. Let it run several minutes while watching from the access side. Only close the wall when you are 100% certain there are zero leaks.
Warning: Do not close the wall until you have verified zero leaks under full pressure for at least 10 minutes. A drip that looks like nothing will saturate the cavity, grow mold, and rot the framing. Do not rush this step. -
Reinstall Trim and Close Access
From the shower side: install the new escutcheon plate, handle, and trim. Run a thin bead of silicone caulk around the escutcheon where it meets the tile to keep water from getting behind it. From the access side: install a drywall access panel (framed panel with a removable door). Much better than patching it closed -- next time the cartridge needs replacing, you just open the panel instead of cutting the wall again.
Tip: A drywall access panel ($10-15) is one of the best investments in future maintenance. Put one behind every shower valve, water heater, and washing machine shutoff. Pays for itself the first time you need it.
Pro Tips
- Try a cartridge replacement first. It is 10x easier, 5x cheaper, and solves 90% of shower valve problems. Only replace the full body if the body itself is damaged.
- Upgrading? Choose a pressure-balancing valve (Moen Posi-Temp, Delta MultiChoice, Kohler Rite-Temp). They maintain constant temperature even when other fixtures run, preventing dangerous hot water surges. Most codes now require them for new installations.
- Soldering in a wall cavity? Flame protector cloth ($5-10) behind the pipe is mandatory. Or skip the torch entirely and use SharkBite fittings.
- Photo everything before you remove the old valve -- pipe routing, depth setting, bracket position. Invaluable references when positioning the new one.
- Going from two-handle to single-handle? You will need to cap the extra hole. A decorative cover plate or small tile patch handles it.
When to Call a Pro
This is one of the few projects where calling a pro is often the right call. Consider a plumber if you are not comfortable with copper pipe or soldering, if the valve is on an exterior wall with limited access, if the pipe routing needs major changes, if the pipes are galvanized steel, or if this is part of a bathroom remodel with the wall already open. The DIY savings ($150-300) need to be weighed against the risk of a leak inside a wall.