Pressure Reducing Valves: How to Adjust and Maintain

A pressure reducing valve (PRV) is a plumbing workhorse that lowers incoming high water pressure to a safe, consistent level for your home. It protects pipes, water heaters, and appliances from strain, and it prevents the banging, dripping, and premature failure that high pressure causes. This guide walks you through what a PRV does, how to adjust it, and how to keep it working—no special tools beyond a couple of wrenches and a pressure gauge.

Ingredients

1 pressure reducing valve (installed on main water line)
1 water pressure gauge (threads onto a hose bib or faucet)
1 adjustable wrench or channel-lock pliers
1 flathead screwdriver (for adjusting the valve)
1 bucket or rag (to catch drips)
Optional: Teflon tape (for re-sealing threads if you remove the gauge)

Instructions

Locate your PRV. It is typically a bell-shaped brass or bronze device on the main water line, often near the water meter or where the pipe enters the house. It has a threaded adjustment screw on top, sometimes under a cap.
Check the current pressure. Screw a water pressure gauge onto a hose bib (outdoor spigot) or a laundry faucet. Make sure no other water is running in the house. Open the faucet fully and read the gauge. Normal household pressure is 40–60 psi (275–415 kPa). If it’s above 80 psi (550 kPa), you need to adjust.
Turn off the main water supply. Close the main shut-off valve, usually near the meter. Open a faucet somewhere in the house to drain the line and relieve pressure.
Loosen the locknut. On most PRVs, there is a locknut (hex nut) just below the adjustment screw. Use the adjustable wrench to loosen it—do not remove it, just loosen so the screw can turn.
Adjust the screw. Turn the adjustment screw clockwise to increase pressure, counterclockwise to decrease. Make small turns (quarter to half turn) and then re-tighten the locknut finger-tight.
Turn the water back on. Open the main valve slowly. Let the system pressurize, then close the faucet you opened earlier.
Re-check the pressure. Read the gauge again. If it’s still too high or too low, repeat steps 3–6 until you hit your target (usually 50–60 psi / 345–415 kPa).
Finalize. Once set, tighten the locknut securely with the wrench. Leave the gauge on for a few minutes to ensure the pressure holds steady. Remove the gauge and close the hose bib.

Tips

Substitution for a pressure gauge: If you don’t have a gauge, you can rent one from a hardware store or borrow from a neighbor. Alternatively, some plumbers offer free pressure checks—but the gauge is cheap (around $10) and worth owning.
Don’t over-tighten the locknut. It only needs to be snug; over-tightening can strip the threads or crack the valve body.
If the valve is old or leaking, replace it. PRVs have a rubber diaphragm that wears out after 10–15 years. If you see water pooling around the valve or hear a constant hissing, it’s time for a new one—adjusting won’t fix a worn-out valve.
Check for thermal expansion. If you have a closed system (check valve or backflow preventer), a water heater can cause pressure spikes. You may need an expansion tank to keep pressure stable.

Serving Suggestions

Once your PRV is set correctly, enjoy the benefits: no more banging pipes, longer life for your water heater and washing machine, and fewer leaks in faucets and toilets. You’ll also notice a steadier shower temperature and less water waste.

Variations

Adjustable vs. fixed PRVs: Some PRVs are factory-set and not adjustable. If yours has no screw, you may need to replace it with an adjustable model to change pressure.
For well systems: If you’re on a well, the pressure switch on the tank controls the range, but a PRV can still be used to fine-tune pressure for the house.
Commercial-grade PRVs: These have a built-in strainer and are more precise, but they cost more and are typically used in larger buildings.

Storage and Reheating

Your PRV doesn’t need “storage”—it’s installed on the pipe. But if you’re replacing it, store the new valve in a dry, temperature-stable place (like a basement shelf) until installation. For maintenance, check the pressure every 6 months and inspect the valve for leaks annually. If you notice the pressure creeping up, re-adjust as described. There’s no “reheating” here, but you can think of the adjustment as a tune-up—do it gently and check the results.

Frequently Asked Questions

Why is my water pressure high even after adjusting?
If you turned the screw counterclockwise and the pressure didn’t drop, the valve may be stuck or worn. Try turning the screw fully counterclockwise and then back clockwise a few times to free it. If that doesn’t work, the diaphragm is likely damaged and the valve needs replacement.

Can I adjust a PRV without a pressure gauge?
You can, but it’s risky—you might set it too high and damage your plumbing. If you don’t have a gauge, you can listen for banging pipes or check faucet flow, but that’s not accurate. The gauge is worth the $10.

What pressure should I set my PRV to?
Most residential systems work best at 50–60 psi (345–415 kPa). If you have older pipes, you might want to stay on the lower end (50 psi) to reduce stress. Never exceed 80 psi (550 kPa), as that can cause premature failure of fixtures and appliances.

How often should I check my PRV?
At least once a year, or if you notice symptoms like water hammer, dripping faucets, or a running toilet. A simple pressure check takes 5 minutes and can save you from costly repairs.

Why is my PRV making a noise?
A hissing or chattering sound usually means the valve is struggling to regulate—often due to debris in the line or a failing diaphragm. Try cleaning the valve (if you’re comfortable) or call a plumber. Ignoring it can lead to failure.

Can I install a PRV myself?
If you’re handy with plumbing, yes—it’s a straightforward job that involves cutting into the main line and soldering or using compression fittings. However, it requires shutting off the water and may need a permit. If you’re not confident, hire a licensed plumber.

More recipes to cook

Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

Spotted an error? Tell us and we will correct it (corrections policy).