Symptoms
- Valve handle won't turn at all
- Valve turns partway then stops
- Valve is old and has likely never been operated
- Visible corrosion or mineral crust around the valve
Likely causes
- CommonMineral buildup on the valve stemDeposits can lock a rarely used valve in place.
- CommonCorrosion on an older valveEspecially common with older compression-style valves.
- PossibleValve simply old and worn outSome valves fail internally and should be replaced rather than forced.
- Less commonPaint or debris sealing the valve in placeCan happen after a remodel if the valve wasn't protected.
What to do
- Apply a penetrating lubricant around the valve stem and let it sit for 10–15 minutes.
- Try turning the valve gently with steady pressure using pliers or an adjustable wrench, avoiding excessive force.
- If it starts to move, work it back and forth in small increments rather than forcing a full turn.
- If it still won't budge, avoid forcing it further since old valves can snap and cause a harder-to-stop leak.
- If you need water off now and the valve won't cooperate, shut off the main water supply to the house instead.
- Plan to have a plumber replace a stuck valve, ideally before it's needed in an emergency rather than during one.
Tools and parts
- Penetrating lubricant
- Adjustable wrench
- Pliers
Quarter-turn shutoff valveSearch: “quarter turn angle stop valve 3/8 compression”
When to call a pro
Call a plumber to replace a stuck shutoff valve, especially before it's urgently needed during a future repair.
Safety
Use caution
Forcing an old, corroded valve can snap the stem and cause an uncontrolled leak; stop and call a plumber if it won't turn with gentle effort.