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.
A pressure reducing valve, also called a pressure regulator, sits just past the main shutoff where water enters the house. Many municipal systems deliver 100 PSI or more to keep distant hydrants supplied, far above what residential plumbing should see. The PRV throttles that down to a steady 45 to 60 PSI using an internal spring and diaphragm. Where the street pressure exceeds 80 PSI, plumbing code requires one, and on those systems the PRV is the single component protecting every fixture in the house.
A PRV is a wear item with a 7 to 15 year life. When the internal diaphragm fails, it usually fails in one of two directions. If it sticks closed or partly closed, the whole house loses pressure at once, the classic symptom homeowners chase for weeks. If it fails open, full street pressure floods the system, and you start hearing water hammer, see toilets running, and find faucets spitting. A pressure gauge reading well outside the 40 to 60 band is the quickest confirmation that the regulator is the suspect.
You can recognize a PRV by its bell or pear shape and the adjustment screw on top. That screw lets a plumber fine-tune the setpoint, but turning it does not fix a failed unit. Once the rubber diaphragm hardens or tears, the valve is replaced rather than rebuilt in most homes. Because it sits on the main line, replacement means shutting the house down briefly, which is straightforward but not a no-tools job.
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- 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.
- 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.