Symptoms
- Water keeps flowing with handle in the off position
- Steady stream rather than a drip
- Problem may follow a period of stiff or gritty handle operation
- Sound of running water even when no fixture is in use
Likely causes
- CommonWorn cartridge that no longer sealsInternal seals degrade until they can't fully block flow.
- CommonDamaged valve seatPitting or debris on the seat prevents a tight seal even with good washers.
- PossibleDebris lodged in the valveSediment or a small particle can hold the valve open.
- Less commonBroken shutoff valve under the sinkRare, but worth checking if the faucet's own repair doesn't help.
What to do
- Turn off the shutoff valves under the sink right away to stop the water waste.
- Remove the handle and inspect the cartridge or stem for debris around the seat.
- Flush the valve body with clean water to dislodge any trapped sediment, then test if debris was the cause.
- If it still won't seal, replace the cartridge, stem, or washer with an exact match for the faucet model.
- Inspect the valve seat for pitting and resurface or replace it if it's rough.
- Reassemble and turn the water back on slowly, watching closely as you test the shutoff.
- If the faucet still won't fully shut off, close the under-sink shutoff valves until it can be repaired.
Tools and parts
- Adjustable wrench
- Screwdriver
- Seat wrench
Faucet cartridge or stemSearch: “faucet cartridge stem replacement kit”
When to call a pro
Call a plumber if replacing the cartridge and cleaning debris doesn't fully stop the flow.
Safety
Use caution
Leaving a faucet that won't shut off unattended can waste large amounts of water and cause overflow; close the under-sink valves if you can't fix it right away.