Quick Answer: For most homes, the Watts LF25AUB-Z3 (3/4") is the regulator to buy. It adjusts from 25 to 75 psi, ships at 50 psi, and parts are easy to find at any supply house. The Zurn Wilkins 70XL is an equally solid choice if that's the brand your plumber stocks. If you'd like a gauge built in so you can set and check it without extra parts, get the Caleffi 535H. Match the valve to your pipe size, not one size bigger.
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Screw a pressure gauge onto a hose bib before you buy anything here. That one test decides whether you need a regulator, and too many people skip it. If the needle sits between 50 and 70 psi, your house is fine and a PRV will just cost you flow. If it's at 85, 100, or swinging higher overnight when the neighborhood stops using water, you have a problem. That pressure wears out toilet fill valves, water heater relief valves, washing machine hoses, and the seals in your softener's control valve.
Softener control valves have a maximum working pressure on the spec sheet. Ours is a rule of thumb, not a code: keep the house at 60 psi or less and the softener, the water heater and every faucet cartridge will last longer. Our softener pressure requirements guide has the minimum and maximum numbers to check on your own unit.
In this guide
What changes when you add a PRV
It goes before the softener. The regulator sits right after the main shutoff, where the service line enters the house. Everything downstream, softener included, sees the lower pressure. Don't put it after the softener. The softener would still be taking the full street pressure.
It probably makes your plumbing a closed system. Most residential PRVs act as a check, so heated water expanding in the water heater has nowhere to go. Your T&P valve drips, or pressure spikes every time the burner runs. Plan on an expansion tank on the cold inlet of the water heater. Many local codes require one when a PRV goes in. That spike can also cause banging pipes, which we cover in water hammer after a softener.
It can be the cause of "low pressure after the softener." A PRV set too low, or one whose strainer screen is clogged, gives you a weak shower that looks like a softener problem. If you added both at the same time, check the PRV setting first. Our low pressure troubleshooting page covers the rest.
Already have a PRV? Signs it's wearing out
A lot of people searching for a regulator already have one, often buried behind a wall panel or in a meter box, and it's 20 years old. Regulators wear out slowly, and the symptoms get blamed on everything else:
- Pressure creeps up overnight. Your gauge reads 55 in the evening and 85 by morning. The seat isn't sealing, so street pressure leaks through when nobody's using water. (Thermal expansion with no expansion tank can look the same, so check the tank first.)
- Pressure collapses with two fixtures running. A worn or scaled-up valve can't open far enough to keep up with demand. On hard water, scale on the internal parts is a common cause, and a softener won't help, because the PRV sits upstream of it.
- Humming or chattering from the valve when a faucet is partly open.
- The water heater relief valve drips after a hot shower, even though the T&P valve itself is fine.
A rebuild kit (diaphragm, seat, strainer) can restore an older Watts or Wilkins if the body is in good shape. Once the valve is past 15 years, or the adjusting screw is seized, replacing it is usually the better spend of your time. That's why it's worth choosing a valve with union connections this time. The next swap won't need a torch or a pipe cutter.
Setting it
- Install a gauge downstream, either on the PRV's gauge port or at the nearest hose bib.
- Open a faucet a little so there's some flow.
- Loosen the locknut and turn the adjusting screw. Clockwise raises pressure on most designs. Check your valve's instructions.
- Set to 50–60 psi, close the faucet, and confirm static pressure doesn't creep upward over the next hour. A reading that keeps climbing points to a worn seat or a thermal-expansion problem.
- Snug the locknut.
The five valves
Watts LF25AUB-Z3 (3/4"): the safe default
This is the PRV plumbers have reached for by habit for decades, and the lead-free LF version is the current one. It adjusts from 25 to 75 psi with a 50 psi factory setting, and it has a union inlet so it's easier to service or swap later. Repair kits are stocked at most supply houses. That counts for something on a part you'll own for 15 years.
Where it falls short: no gauge in the box, and the 75 psi top end won't suit anyone who wants unusually high house pressure for irrigation. That's rare. Also check the listing's connection type. Watts sells this valve in several end configurations (threaded union, sweat union, PEX), and buying the wrong one means extra adapters.
Zurn Wilkins 34-70XL (3/4"): the other plumber standard
Same job, different brand loyalty. Supply-house specs list a 25–75 psi adjustable range, a 50 psi factory setting, a 300 psi rating and a 140°F max temperature. It's listed to NSF/ANSI 61 and 372 and to ASSE 1003. Its union FNPT inlet makes future swaps simple. Pick it over the Watts if that's what your local supply house carries repair kits for. Zurn sells the RK34-70XL kit for the 3/4" 70-series valves.
Same caveat as the Watts: no gauge, and the version you buy needs to match the piping you have.
Caleffi 535H PresCal with gauge (3/4" sweat): set it by eye
The Caleffi is a pre-calibrated valve with its own gauge. Caleffi's spec sheet lists a 15–90 psi setting range, a 45 psi factory setting, a 0–100 psi gauge, and a removable cartridge you can replace inline. It's certified to ASSE 1003, CSA B356 and NSF/ANSI 61/372. The gauge makes setup simple. It also gives you a quick daily check that pressure hasn't drifted, which is the first warning that the seat is wearing.
The trade-off: Caleffi is less common at big-box stores, so a replacement cartridge may need to be ordered. This listing is the sweat version. Caleffi also sells NPT, press and PEX variants, so buy the one that matches your pipe.
Honeywell DialSet DS06 (3/4"): easiest adjustment
Honeywell's DialSet puts a numbered dial on the valve, so you can set pressure without the "turn, check the gauge, turn again" loop. This one has double-union connections on both ends, which makes it the easiest of the five to swap out later without cutting pipe. That's handy for DIYers who'd rather set a number than fiddle with a screw and locknut.
The catch: a dial on a regulator tells you where it's set, not what pressure the house is actually seeing. Still confirm with a gauge after install. The listing title mentions both female NPT and sweat, so read the connection details before ordering.
Watts LF25AUB-Z3 (1"): don't choke a 1" line
The same valve family in 1", with a threaded female union inlet and female NPT outlet, listed at 25–75 psi adjustable (50 psi standard setting) and rated for inlet pressures up to 400 psi. Watts also lists a bypass feature that lets thermal-expansion pressure flow back through the valve into the main. If your service line and softener are 1" (common with a 48,000-grain-plus softener or two-plus bathrooms), a 3/4" PRV becomes the narrowest point in the house. Spend a little more and keep the bore matched.
If you're on 3/4" copper from the meter, though, buying the 1" just to feel safe adds two reducers and gets you nothing.
Sizing: what pipe size really means here
The PRV should match the service line, not the faucet count. A worked example: a three-bath house on a 1" copper main, with a 48,000-grain softener on a 1" valve and a 1" bypass. Put a 3/4" PRV ahead of that and you've bottlenecked everything you upsized. During a morning with two showers and a dishwasher running, the PRV drops pressure more than the softener does. Go 1".
Now take a two-bath house on 3/4" PEX from the meter with a 32,000-grain softener on a 3/4" valve. A 3/4" PRV is right. Installing a 1" "for future-proofing" adds two reducers, and the regulator, working at the low end of its range, can be less stable at small flows.
If you're doing this yourself, budget an afternoon. Shut the main, drain the house, cut in the valve with unions, add the gauge, and set the pressure. If the main shutoff is old and doesn't close fully, or there's no shutoff at the curb you can reach, call a plumber. Nothing about a PRV is hard, but working on a live service line is no fun.
Which one, quickly
- Typical 3/4" house, DIY or plumber install: Watts LF25AUB-Z3 3/4".
- Your plumber prefers Zurn: Wilkins 70XL. There's no reason to argue.
- You want to see pressure every day: Caleffi 535H with gauge.
- You want to set a number, not chase a screw: Honeywell DialSet.
- 1" main and 1" softener valve: Watts LF25AUB-Z3 1".
A PRV also isn't backflow protection. If your utility or local code requires a backflow preventer, that's a separate device. We cover how it interacts with a softener in water softener backflow protection.