What Is a Fixture Shutoff Valve (Stop Valve)?
A fixture shutoff valve, also called a stop valve or angle stop, is a small valve that isolates a single fixture from the water supply. They are located under sinks and behind toilets, typically one for cold and one for hot. Closing one lets you work on or stop a leak at that fixture without cutting water to the entire building.
Why they matter in an emergency
A working fixture shutoff is what converts an emergency into an appointment. If a supply line under a sink fails and you can close the stop valve, the water stops and nothing further is damaged, and the repair can happen at standard rates on a weekday.
If the stop valve has seized, which is common, your only option is the main, and the household loses all water until a plumber arrives. That difference is typically several hundred dollars.
Multi-turn versus quarter-turn
Older multi-turn compression stops have a small round handle and use a rubber washer that hardens over time. They seize reliably and often leak from the packing once moved.
Quarter-turn ball stops have a lever and a ball mechanism that does not depend on a compressible washer. They are far more reliable and cost only a few dollars more. When a plumber is already working under a sink, upgrading the stops is inexpensive and worth doing.
Frequently asked questions
Should I exercise my shutoff valves?
Yes. Turning each one fully closed and open again once or twice a year keeps them from seizing, and it tells you which have already failed at a moment when that is merely useful information. It is one of the highest-value five-minute maintenance habits in a house.
My stop valve leaks now that I turned it. What do I do?
That is typical of old compression stops whose packing has hardened. Tightening the packing nut slightly often stops it. Either way the valve should be replaced, ideally with a quarter-turn ball stop, and it is a small job worth doing before the next emergency.
See also
Related services
- Emergency Fixture Repair and InstallationRepair and replacement of faucets, shutoff valves, supply lines, garbage disposals, and other fixtures, including failed connections that leak.
- Emergency Toilet RepairRepair of overflowing, leaking, or non-functioning toilets, including wax ring replacement, valve repair, and clearing blockages.