A shut-off valve usually leaks because a rubber washer or seal inside it has worn out, the packing around the handle has loosened, or the valve body has corroded with age. Valves that are rarely turned are especially likely to drip once someone finally uses them.
Where the Water Comes From
Look closely to see where the drip starts:
- Around the handle stem: the packing or packing nut may be worn or loose.
- At the connection to the pipe: the fitting or compression nut may not be sealed well.
- From the valve body: corrosion or a crack may have weakened the metal.
- From the supply line: the hose to the sink or toilet may be the real problem.
Why Old Valves Fail
Many homes have small valves under sinks and behind toilets that have not been touched in years. Minerals build up inside, and the rubber parts dry out. When the handle is finally turned, the stiff parts can shift and start leaking. Older multi-turn valves are more likely to do this than newer quarter-turn valves.
What You Can Do Now
If the valve drips only when it is open, you may be able to close it and use another fixture for a while. Put a small bowl under it and check it often, emptying it before it overflows. If the leak is steady or gets worse, close the main shut-off for the house.
Avoid forcing a stuck handle with pliers or a wrench. Too much force can snap the stem and turn a slow drip into a spray.
A worn valve is often best replaced rather than repaired. Our page on fixing household water leaks explains what that visit usually involves.
If you have several old valves around the house, it may make sense to replace them together. If that sounds useful, ask a local plumber to check them all with one call to (833) 603-1840.