Symptoms
- Greenish or white crusty buildup visible on the stem when removed
- Persistent leaking even after replacing washers
- Handle feels gritty or rough to turn
- Valve is old, often original to the home
Likely causes
- CommonLong-term mineral and metal corrosion on an aging stemBrass and steel stems corrode over decades, especially with hard water exposure.
- PossibleDissimilar metal reaction between stem and fittingsCertain metal combinations can accelerate corrosion through galvanic reaction.
- PossibleChronic moisture exposure inside the valve bodyA slow, long-standing drip can accelerate corrosion of the stem far faster than normal use.
What to do
- Shut off water to the shower fully before disassembly.
- Remove the handle, trim, and packing nut to access the stem.
- Unscrew and remove the stem, noting the direction and any thread pattern for replacement matching.
- Take the old stem to a hardware or plumbing supply store to find an exact match, or identify the brand and model for an online order.
- Clean the valve body threads of any corrosion residue with a wire brush before installing the new stem.
- Install the new stem with fresh plumber's tape or pipe joint compound on the threads as appropriate.
- Reassemble, turn water on slowly, and check thoroughly for leaks at the stem and packing nut.
Tools and parts
- Adjustable wrench
- Wire brush
- Packing wrench (if needed)
Replacement faucet stemSearch: “shower faucet stem replacement”
When to call a pro
Call a plumber if the valve body itself shows corrosion damage beyond the stem, since the whole valve may need replacement.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.