Water Pressure Regulators: What They Are and How They Work

A water pressure regulator reduces the flow of water into the home to limit the strain on the plumbing infrastructure. High water pressure can cause many plumbing problems, so it is important to keep it under control.

Learn about water pressure regulators, how they work, why you need one, and how to replace one that's defective.

What Is a Water Pressure Regulator?

A water pressure regulator is a valve that reduces the incoming water pressure to a manageable level for the home plumbing infrastructure. Water pressure regulators are installed where the main water line enters the home, just after the main shutoff valve.

Although it is not necessary for every plumbing installation, a water pressure regulator can be essential when the municipal water supply enters the home at a very high pressure or where water pressure is irregular.

If the water pressure is too high, it can cause significant damage to the valves, faucets, appliances, pipes, and plumbing fittings. When the system is protected by a water pressure regulator, there is less stress on the inner valves of appliances, faucets and shutoff valves will be less likely to leak, and fluctuations in water pressure are evened out.

Normal vs. High Water Pressure

Most home plumbing fixtures are designed to work best at a pressure of about 50 psi (pounds per square inch).

It is common for municipal water supplies to enter the home with pressures as high as 150 or 200 psi. If such high pressure is present regularly, the strain can eventually cause joints to fail, faucets and other fixtures to leak, and appliances to break down.

What a Water Pressure Regulator Looks Like

A water pressure regulator is a dome-shaped brass fitting generally found just past the main shutoff valve, where the main water line enters the house. It usually has an adjustment screw on top.

Inside, a water pressure regulator has a variable spring-loaded diaphragm that automatically widens and narrows depending on the amount of water pressure entering the valve.

How a Water Pressure Regulator Works

A water pressure regulator can both reduce high water pressure and increase low water pressure.

Reducing High Pressure

1. Water enters the regulator at high pressure.
2. The regulator's inner mechanism constricts the diaphragm.
3. The flow passage is narrowed.
4. Water pressure is reduced to a range of 50 to 80 psi.

Increasing Low Pressure

1. Incoming water pressure drops.
2. The diaphragm opens.
3. The flow passage is widened, so more water flows through the valve.

Adjusting the Pressure

An adjustment screw on the top of the regulator can be tightened to increase the tension on the inner spring. This reduces the water pressure as it exits the valve).

Alternatively, the screw can be loosened to allow water to flow more freely through the valve, increasing the outgoing water pressure.

When You Need One

To determine whether you need a water pressure regulator, test the water pressure in your house's main water supply.

Screw the pressure gauge onto any hose bib or washing machine faucet. Turn on the cold water tap to measure the water pressure. If the pressure is between 40 and 60 psi, there is no need for a regulator. However, if the water pressure is over 80 psi, it is probably causing excessive stress on pipes, fittings, and fixtures.

City water pressure can fluctuate considerably, often increasing at night when the overall load goes down. So, test at various times of the day.

During the test, ensure that water isn't being used anywhere else in the house, such as at garden spigots or appliances.

Learn If You Have a Water Pressure Regulator

To determine if you have a water pressure regulator, first locate where the main water line enters the building and find the main shut-off valve for the home. Typically, if you have a water pressure regulator it will be installed directly after the main shut-off valve.

If you cannot locate your main shut-off valve where the main line enters the home, then you should do a thorough inspection of the basement, garage, or crawlspace to find this valve. Alternately, the shut-off valve location may be listed in a home inspection report.

Once you have tracked down the shut-off valve, check the pipes downstream of the valve for a water pressure regulator. If you cannot find one after a lengthy investigation then it's likely that your home does not have a water pressure regulator.

How Long They Last

A water pressure regulator can last from four to 12 years in a healthy plumbing system. However, most manufacturers recommend replacing them about once every five years to limit the potential damage high water pressure could cause to the plumbing infrastructure.

When to Replace a Water Pressure Regulator

You should consider replacing the water pressure regulator if you notice any of these issues:

• Water pressure fluctuates with no obvious pattern.
• Significantly higher or lower water pressure throughout the home.
• Leaking pipes.
• Knocking sounds from the pipes (water hammering).
  

How to Replace a Water Pressure Regulator

Replacing an existing water pressure regulator is relatively easy. A water pressure regulator should be installed immediately after the main valve, using a set of threaded couplings to secure the water pressure regulator.

1. Turn off the water to the home at the main shut-off valve.
2. Open the faucet nearest the main shut-off valve to drain excess water from the system.
   
3. Position a bucket and towel under the existing water pressure regulator.
4. Use a set of Channellock pliers to loosen the threaded couplings and remove the old water pressure regulator.
5. Place the new water pressure regulator in position and hand-tighten the threaded couplings.
6. Use the Channellock pliers to finish tightening the couplings.
7. Turn the water on at the main shut-off valve and check for leaks.
8. Make sure to turn off the faucet you opened after allowing any air in the system to escape.
   

How to Install a Water Pressure Regulator

Unless you are experienced at plumbing work, it's best to call a plumber. The installation may require repositioning the main water shutoff valve to create the necessary space for the water pressure regulator.

1. To get a baseline water pressure reading, take a pressure measurement with a pressure gauge from a hose bib or washing machine faucet.
2. Locate the main water shut-off valve for the home and turn the water off.
3. Open the faucet nearest to the main shut-off valve to drain the water from the system.
4. Use a tape measure to measure the length of the water pressure regulator with the threaded couplings attached, then mark this measurement on the pipe just after the main shut-off valve.
5. Place a bucket and towel under the pipe, then use a pipe cutter to cut the pipe according to your previous measurements. The couplings will slide onto the ends of the remaining pipe, so ensure you don't remove too much pipe during this step.
6. Use a grit cloth and a wire brush to clean the pipe and fittings, then apply flux paste to the pipe and fitting to help with the soldering process.
7. Slide the threaded couplings over the pipe and apply heat to the fitting with the blow torch.
8. When the fitting is hot enough, apply solder to the connection, allowing it to flow into the narrow gap between the fitting and the pipe. Repeat this process with the second coupling, then wait for the metal to cool down.
9. Once the threaded couplings are cool, you can put the water pressure regulator in place and hand-tighten them. Then, you can finish tightening the couplings with the Channellock pliers.
10. Turn on the water at the main shut-off valve and check for any leaks.
11. Close the faucet you opened after allowing any trapped air to escape from the system.
12. After installation, test the water pressure.
13. Adjust the regulator if necessary. To adjust, loosen the locknut on the adjustment screw, then turn the screw up or down until the water pressure is at the desired level, as measured by a pressure gauge attached to a threaded hose bib somewhere in the home.
    

Cost of Water Pressure Regulators

The cost of a water pressure regulator installation depends on whether you hire a professional plumber to complete the work or if you have the necessary skills, knowledge, and experience for a DIY installation. Typically, water pressure regulators cost about $50 to $100 on average, though you could end up paying up to $200 depending on the size of incoming water line.

If you choose to complete this job independently, you must purchase the necessary parts and tools, including threaded couplings, a pipe cutter, grit cloth, flux paste, solder, and a blow torch.

If you don't already have the tools in your workshop, this can significantly affect the cost. However, if you decide to hire a plumber to install the water pressure regulator, the average cost for installation ranges from $250 to $450.