Definition
The bell-shaped valve that drops incoming street water pressure to a safe household level — code requires regulation above 80 psi; failed PRVs quietly destroy fixtures and water heaters.
What pressure should a home actually run at?
50 to 60 psi is the sweet spot. The plumbing code requires pressure regulation when the street supply exceeds 80 psi, because sustained high pressure hammers everything downstream: faucet cartridges fail early, supply hoses burst, water heater relief valves weep, and pinhole leaks accelerate. Hillside homes fed from high-elevation mains can see well over 100 psi at the meter.
How do you know your PRV is failing?
PRVs wear out in 10–15 years, and they fail in both directions. Rising pressure shows up as banging pipes, a dripping water-heater relief valve, and fixtures failing in clusters; falling pressure shows up as the weak showers people blame on the city. A $15 gauge on a hose bib answers it in two minutes — read it at night, when municipal pressure peaks.
What does replacement involve?
The PRV sits on the main line right after the shutoff, and a like-for-like swap is a few hours of licensed work. It's also the moment to add or verify a thermal expansion tank at the water heater — a regulated (closed) system traps expansion pressure that the street connection used to absorb, and code pairs the two for exactly that reason.
In the Puget Sound
Seattle and Eastside hillside neighborhoods fed by gravity mains routinely meter above 80 psi at the low end of the hill — the classic profile where an aging PRV is the difference between quiet plumbing and a slow-motion fixture massacre.
Related terms
Go deeper on PRV (pressure reducing valve)
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Trade: Plumbing