Angle Stop / Fixture Shutoff
The small individual shutoff valve under a sink or behind a toilet that stops water to that one fixture without shutting down the whole house.
An angle stop is the little valve you see where the supply line meets the wall under a sink or behind a toilet. It is called an angle stop because the inlet and outlet sit at ninety degrees to each other, turning water from a vertical pipe in the wall to a horizontal connection at the fixture. Its job is isolation: when a faucet drips or a toilet fill valve fails, you close the angle stop and work on that fixture while the rest of the house keeps running.
These valves come in two styles. Older multi-turn stops use a small round or oval handle that you twist several times, and like full-size gate valves they tend to seize or weep after years untouched. Quarter-turn ball stops, with a small lever, are the reliable modern choice and what plumbers install during any faucet or toilet job. A stop that will not turn, or one that drips from the packing nut when you finally use it, should be replaced rather than forced.
Angle stops are cheap parts that prevent expensive problems. Because they let you isolate one fixture, you can swap a faucet or repair a running toilet without finding and using the main shutoff. The catch is that homeowners often discover a frozen or leaking stop at the worst moment, mid-repair, with water still on. That is why plumbers routinely replace aging stops as part of any under-sink or toilet work rather than reusing a questionable valve.
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- PSI (Pounds per Square Inch) : The standard unit for measuring water pressure, where residential plumbing typically targets 40 to 60 PSI and code limits incoming pressure to 80 PSI.
- Pressure Reducing Valve (PRV) : A spring-loaded valve installed on the main line that lowers high municipal pressure to a safe household level, usually preset around 50 PSI.
- Water Meter : The utility-owned device that measures how much water your home uses, usually located at the property line in a buried box or in the basement.
- GPM (Gallons Per Minute) : A measure of flow rate, the volume of water a fixture or system delivers each minute, distinct from pressure, which is the force behind it.