How to Adjust a Water Pressure Reducing Valve (PRV)

The first critical step is to establish a baseline measurement of your home's current water pressure. First, ensure no water is running anywhere in the house (e.g., toilets, faucets, showers, washing machine). Locate an exterior hose bib (spigot) or an indoor laundry sink faucet. Screw the water pressure gauge onto the faucet's threads, ensuring a snug, hand-tight connection. Open the faucet all the way. The needle on the gauge will immediately display the home's static water pressure in PSI (pounds per square inch). Note this number down. A reading above 75-80 PSI is too high and confirms the need for adjustment.

Locate the water pressure reducing valve. It is typically a bell-shaped brass valve installed on the main water line shortly after the main shut-off valve and the water meter. Once you've identified the PRV, examine the top of the 'bell'. You will see an adjustment mechanism, which in this case consists of a threaded bolt protruding from the top and a separate locknut around its base. Before making any changes, it's wise to mark the current position of the bolt with a permanent marker. Use an adjustable wrench or a pair of channel-lock pliers to loosen the locknut. You'll need to turn the locknut counter-clockwise. You may need to hold the adjustment bolt steady with a second tool (like a screwdriver or another wrench) while loosening the nut to prevent it from turning.

With the locknut loosened, you can now adjust the pressure. To decrease the water pressure (our goal), use a wrench or screwdriver to turn the adjustment bolt counter-clockwise ('lefty-loosey'). To increase pressure, you would turn it clockwise ('righty-tighty'). Make only a small adjustment at first—a quarter-turn or half-turn is sufficient. It is crucial not to make large adjustments at once, as this can cause a dramatic and unpredictable change in pressure.

After making an adjustment, you must test the pressure again to see the result. However, the system's pressure won't update until water has flowed through the valve. Go to a faucet inside the house (ideally on an upper floor) and turn it on for about 20-30 seconds. This allows water to flow through the newly adjusted PRV and stabilizes the pressure throughout your home's plumbing. Turn the faucet off, then return to your water pressure gauge. The needle will now show the new, adjusted static pressure. Compare this reading to your initial measurement and your target pressure (50-60 PSI).

It is unlikely you will hit the perfect pressure on the first try. You will need to repeat the adjustment and testing cycle. Go back to the PRV, turn the adjustment bolt another small increment (Step 3), then go run a faucet and re-test the pressure (Step 4). Continue this iterative process until the gauge consistently reads within your target range of 50-60 PSI. Once you are satisfied with the pressure, the final step is to secure your setting. While holding the adjustment bolt stationary with one tool, use your wrench to tighten the locknut by turning it clockwise. It should be snug, but do not overtighten it, as this can damage the threads. Once the locknut is tight, the adjustment is complete. You can now remove the pressure gauge from the faucet.