How to Adjust a Pressure Reducing Valve
Updated February 20, 2026
Test your water pressure, find the PRV on your main line, and adjust it to a safe 50-60 PSI -- before high pressure wears out your fixtures, appliances, and water heater.
Overview
High water pressure is a silent destroyer. It wears out faucet cartridges faster, stresses pipe joints, causes banging pipes (water hammer), and can trip your water heater's relief valve. Most people do not even realize their pressure is too high until things start breaking. Your pressure reducing valve (PRV) -- a bell-shaped brass fitting on the main water line -- is the one thing keeping municipal pressure (which can push 80-150+ PSI) down to a safe level for your home. The sweet spot is 50-60 PSI. Adjusting it is literally turning a screw, but you need a $10-15 pressure gauge so you know what you are working with. The whole job takes 15-30 minutes.
What You'll Need
Safety First
- Never set the PRV above 80 PSI. That is the code maximum for a reason -- anything higher chews through faucet cartridges, stresses appliance inlet valves, and shortens the life of everything connected to your water supply. Aim for 50-60 PSI.
- If the PRV is 15+ years old, corroded, or the adjustment screw will not budge, do not force it. A seized screw can snap off and leave you with zero pressure regulation and full street pressure flowing into the house. That PRV needs replacement, not adjustment.
Step-by-Step Instructions
-
Test Your Current Water Pressure
Grab a water pressure gauge ($10-15 at any hardware store) and screw it onto an outdoor hose bib or a laundry faucet with a hose thread. Make sure nothing else in the house is using water -- no faucets, no toilets filling, no dishwasher or washing machine running. Turn on the faucet and read the gauge. Here is what the numbers mean: 40-60 PSI is the normal range, below 40 is too low (weak flow at fixtures), 60-80 is on the high side but acceptable, and above 80 means you need to turn the PRV down or it may be failing.
Tip: Test at different times of day. Municipal pressure fluctuates -- it is usually higher at night when demand is low and lower during peak morning and evening hours. Your highest reading is what matters, because that is the maximum force your plumbing is dealing with. -
Locate the Pressure Reducing Valve
Follow the main water supply line where it enters your house. The PRV is usually right after the main shut-off valve. In basement homes, look near where the line comes through the foundation wall. In slab homes, check near the water meter or in a utility closet. You are looking for a bell-shaped or dome-shaped brass fitting about 3-4 inches across with a bolt or screw on top -- that is the adjustment mechanism. There is usually an arrow on the body showing flow direction. If you cannot find one, your home may not have a PRV, which is fine if your pressure is naturally below 80 PSI.
Tip: No PRV but your pressure is above 80 PSI? You need one installed. The valve itself is $50-100 and professional installation runs $200-400. Without one, that high street pressure is slowly destroying every fixture and appliance in your plumbing system. -
Adjust the PRV
Look at the bolt or screw on top of the PRV bell. Most have a locknut you need to loosen first -- use an adjustable wrench and turn it counterclockwise. Then turn the adjustment screw: clockwise increases pressure, counterclockwise decreases it. Go slow -- a quarter turn at a time. After each adjustment, walk over to your pressure gauge and check the reading (you may need to open and close the faucet to let it stabilize). Keep tweaking until you hit your target -- 50-60 PSI works for most homes. Once you are there, snug up the locknut to lock the setting.
Tip: If the gauge reading fluctuates wildly or creeps right back up after you adjust it, the PRV's internal diaphragm or spring is worn out. No amount of adjusting will fix that -- the valve needs to be replaced. Most PRVs last 10-15 years before the internals give out. -
Verify and Monitor
Leave the gauge attached and check the reading after 30 minutes, an hour, and again the next morning. It should hold within a few PSI of where you set it. If you set it to 55 PSI and it reads 70 the next morning, the PRV is not holding -- either it needs replacement or you are dealing with thermal expansion (see pro tips). Walk around and test a few faucets and showers too. If you dropped the pressure significantly -- say from 90 to 55 -- fixtures will feel like they have less flow. That is normal and actually a good thing for the longevity of your plumbing.
Tip: Hang onto that pressure gauge and check your pressure every 6 months. PRVs weaken gradually over time, letting more pressure through as the spring fatigues. Catching a slow creep early saves you from blown supply lines and tripped T&P valves down the road.
Pro Tips
- Pressure fine when the water heater is cold but spikes above 80 PSI after it heats up? That is thermal expansion, not a bad PRV. Water expands as it heats, and in a closed system (most homes with a PRV and check valve), that expanded water has nowhere to go. The fix is a thermal expansion tank ($30-50) on the cold inlet of the water heater -- not a PRV adjustment.
- Every homeowner should own a $10-15 pressure gauge. It screws onto any hose bib and gives you instant insight into your system. High pressure quietly destroys things -- you will not notice it until faucet cartridges and supply lines start failing years earlier than they should.
- If you end up replacing the PRV, spend a little extra and get one with a built-in pressure gauge (Watts LFN45B or similar, $40-60). You can check your pressure anytime just by looking at the valve. Worth every penny.
- On a well? Your pressure is not controlled by a PRV -- it is set by the pressure switch and pressure tank on the well pump. Typical well systems run 40-60 PSI, cutting in at 40 and out at 60. Check your well pump documentation for adjustment procedures.
- After dialing the PRV down, your ice maker, washing machine, and dishwasher may fill a bit slower. Totally normal. These appliances work fine anywhere from 20-120 PSI, and the lower pressure extends the life of their inlet valves and hoses.
When to Call a Pro
The adjustment itself is straightforward DIY. Call a plumber if the PRV needs full replacement (that means soldering or compression fittings on the main line), if you need a thermal expansion tank installed, if your home does not have a PRV and needs one, or if the PRV body itself is leaking (internal failure -- not fixable with adjustment).