Symptoms
- Leak appears at the valve stem when turning the handle
- No leak when the valve is left alone
- Valve is old or rarely operated
- Small drip forms around the valve body after use
Likely causes
- CommonWorn packing nut sealThe seal around the valve stem dries out over years of sitting unused.
- CommonFailing internal washerSimilar to a faucet washer, it wears with age and use.
- PossibleCorroded valve bodyEspecially in older galvanized or brass valves.
- PossibleLoose packing nutCan sometimes just need tightening rather than replacement.
What to do
- Turn off the main water supply to the house if the valve leaks significantly when operated.
- Try tightening the packing nut just behind the valve handle a quarter turn with a wrench.
- Operate the valve again gently to see if the leak has stopped or reduced.
- If it still leaks, the packing or internal washer likely needs replacing, which usually means replacing the whole valve since these are rarely serviceable individually.
- With the main water off, unscrew the old valve and supply line, then install a new quarter-turn shutoff valve.
- Apply plumber's tape to threaded connections and tighten firmly but not excessively.
- Turn the main water back on and test the new valve for smooth operation with no leaks.
Tools and parts
- Adjustable wrench
- Plumber's tape
- Pipe cutter (if valve is soldered)
Quarter-turn shutoff valveSearch: “quarter turn angle stop valve”
When to call a pro
Call a plumber if the valve is soldered to copper pipe rather than a compression fitting, since that requires sweating a new joint.
Safety
Use caution
Turn off the main water supply before working on the valve itself, since it's the last point of control before the leak.