Pressure Reducing Valves
Updated February 20, 2026
Automatically reduce incoming water pressure to a safe, consistent level. Protect plumbing fixtures and appliances from damage caused by high pressure.
Overview
Pressure reducing valves (PRVs) reduce incoming municipal water pressure to a safe level for household plumbing. Most homes should have pressure between 40-60 PSI. Municipal supply can be 80-150+ PSI -- too high for residential pipes, fittings, and appliances. The PRV is a spring-loaded valve installed on the main water line that automatically restricts flow to maintain a set outlet pressure. Adjustable via a screw on top. Every home with incoming pressure above 80 PSI needs one. Code requirement in most jurisdictions.
Pros & Cons
- Protects plumbing
- Reduces water waste
- Extends fixture life
- Reduces flow rate
- Needs periodic adjustment
- Can fail and restrict flow
Key Features
- Automatically reduces incoming water pressure to a set outlet pressure
- Adjustable output: typically set to 50-60 PSI for residential use
- Spring-loaded diaphragm mechanism responds instantly to pressure changes
- Installed on the main water line after the meter and before the first branch
- Creates a closed system -- requires an expansion tank on the water heater to absorb thermal expansion
Sizing & Selection
3/4 inch for most residential main lines. 1 inch for larger homes or high-flow applications. The PRV must be sized to handle the peak flow demand of the house without excessive pressure drop. Most residential PRVs handle 5-25 GPM, which covers typical household demand.
Installation
Install on the main water line after the meter and main shut-off, before any branch lines. The arrow on the valve body indicates flow direction (from street to house). Threaded or soldered connections. Once installed, adjust the output pressure with the adjusting screw (clockwise increases pressure, counterclockwise decreases). Verify with a pressure gauge.
Maintenance
- Test output pressure annually with a gauge. If pressure has drifted from your set point, the PRV may be failing.
- PRVs last 7-12 years on average. Budget for replacement proactively.
- Signs of failure: pressure fluctuations, water hammer returning, T&P valve dripping on the water heater.
- When replacing, also check and recharge the expansion tank -- the two work together.
Buying Tips
- Watts and Zurn are the two most common residential PRV brands. Both are reliable.
- Buy a PRV with a built-in strainer to prevent debris from damaging the diaphragm.
- A pressure gauge () is essential for setup and ongoing monitoring. Buy one and keep it.
- When installing a PRV, install an expansion tank on the water heater at the same time. A PRV creates a closed system, and thermal expansion needs somewhere to go.
- If your home has an existing PRV and you are experiencing pressure problems, replacement is usually the answer. PRV internals are not field-serviceable on most residential models.