PRV Testing & Adjustment
Updated February 20, 2026
Municipal water pressure can run 80-150 PSI at the main. Your plumbing system is designed for 40-60 PSI. That's what the pressure reducing valve does -- it steps down the incoming pressure to a safe level. When the PRV fails, high pressure stresses every fitting, hose, and valve in the house. Faucets drip, toilets run, supply hoses burst, and water heater T&P valves discharge. Testing your PRV once a year catches failures before they damage your system.
Overview
Municipal water pressure can run 80-150 PSI at the main. Your plumbing system is designed for 40-60 PSI. That's what the pressure reducing valve does -- it steps down the incoming pressure to a safe level. When the PRV fails, high pressure stresses every fitting, hose, and valve in the house. Faucets drip, toilets run, supply hoses burst, and water heater T&P valves discharge. Testing your PRV once a year catches failures before they damage your system.
What to Know
Step by Step
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Check current pressure
Thread a pressure gauge onto an outdoor hose bib or the washing machine cold water connection. Open the valve. Read the gauge. Do this with no water running in the house for the most accurate reading. If it's above 60 PSI, your PRV needs attention.
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Adjust the PRV
The adjustment bolt on top of the PRV controls the output pressure. Loosen the locknut. Turn the bolt clockwise to increase pressure, counterclockwise to decrease. Make small adjustments -- a quarter turn at a time. Check the gauge after each adjustment. Target 50 PSI for most homes.
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Check for PRV bypass
Close all fixtures, check the gauge, then wait 5 minutes. If the pressure climbs significantly, the PRV isn't holding -- its internal seat is worn and pressure is creeping through. The PRV needs replacement, not adjustment.
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Test at different times
Municipal pressure can vary throughout the day -- lower during peak usage (morning, evening) and higher overnight or midday. Test at different times to understand your pressure range. If it varies widely even with a PRV, the PRV may be struggling.
Pro Tips
- Keep a pressure gauge permanently installed on a hose bib. Checking pressure takes 3 seconds when the gauge is always there.
- When replacing a PRV, upgrade to a model with a built-in gauge or gauge port.
- If you have a thermal expansion tank on your water heater, check its air charge whenever you test the PRV. The two systems work together.
- Write the pressure reading and date on a sticker near the PRV each time you test. Trends tell you when the PRV is starting to fail.
Mistakes to Avoid
- Ignoring high water pressure because everything seems to work fine. The damage is cumulative and shows up as leaks and failures over time.
- Adjusting the PRV too high because you want stronger shower pressure. 60 PSI is the safe maximum.
- Not testing the PRV after replacing a water heater, washing machine, or other appliance. Installation work can disturb the PRV.
- Confusing a thermal expansion issue with a PRV failure. If pressure is high only on the hot side, the expansion tank may be the problem.
When to Call a Pro
PRV replacement is a moderate DIY project but requires shutting off the main, cutting or disconnecting pipe, and soldering or using compression fittings. If you're not comfortable with that, a plumber can swap a PRV in about an hour for $200-$400 including parts.
Bottom Line
Buy a $10 pressure gauge and check your water pressure once a year. If it's above 60 PSI, adjust or replace the PRV. High pressure is the silent destroyer of plumbing systems -- it causes every other component to fail faster.