Repair Water Pressure Regulator & Pressure Reducing Valve

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Bad water pressure regulator:

How to diagnose and fix or replace a bad water pressure regulator. This article describes Diagnosing a Bad Water Pressure Regulator - how to diagnose the loss of water pressure and the need for a replacement water pressure regulator. The process of water pressure problem diagnosis and the costs of the repair are explained.

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What is a Water Pressure Regulator or Pressure Reducing Valve, Where are They Installed, Why?

Water pressure regulator control (C) Daniel FriedmanWater pressure regulators are devices that protect building plumbing systems from excessive water pressure damage by reducing incoming high water main pressure (that can be more than 150 psi in some communities) to a safe level (typically 50 psi) in the building.

Why are water pressure regulators installed on water supplies? Often municipal water supply pressure can run quite high, say over 80 psi and in some communities, more than 150 psi.

Our photo (left) shows typical incoming municipal water piping at a building. From left to right we see a main water shut off valve, a water meter (wires lead to an outdoor water meter reading device), a water pressure regulator, and water piping rising into the building.

This high pressure would cause leaks at many ordinary residential plumbing fixtures like sink and tub faucets or toilets.

So the building may have a pressure regulator installed, usually right after the water meter where water enters the building.

Building Code Requirement for Pressure Reducing Valves

In fact most national and local plumbing codes require that a water pressure reducing valve should be installed at buildings where municipal water supply pressures (in the water main in the street) exceed 80 psi. Excessive water pressures can burst pipes, cause dripping faucets, and can even cause rupture and explosion of both cold water pressure tanks and hot water storage tanks.

Examples of Pressure Reducing Valves Used to Regulate Municipal Water Supply Pressure

According to Watts Corporation, a producer of water pressure reducing valves,

There are two types of water pressure reducing valves, direct acting and pilot operated. Both use globe or angle style bodies. Valves used on smaller piping diameter units are cast from brass; larger piping diameter units are made from ductile iron. Direct acting valves, the more popular type of a water pressure reducing valves, consist of globe-type bodies with a spring-loaded, heat-resistant diaphragm connected to the outlet of the valve that acts upon a spring. This spring holds a pre-set tension on the valve seat installed with a pressure equalizing mechanism for precise water pressure control.

Watts produces a Watts Governor 80™ used for this purpose, but other manufacturers also produce a wide variety of water pressure regulators.

For very high incoming water supply pressures, a two-stage serial reduction method is used: two pressure reducing regulating valves are installed in series. The first pressure reducing vave (for example a Watts Model U5B) reduces incoming water pressure to 150 psi, and the second valve reduces water pressure to 50 psi.

If your building already has a water pressure gauge installed, it may be defective or it may be set too high. The articles listed just below discuss how to adjust a water pressure regulator:

Expansion tanks to relieve high water pressure:

Water pressure regulator (C) Daniel FriedmanAn alternative to installing or changing a water pressure regulator when building water pressure is occasionally 80 psi or higher is the installation of an expansion tank to temporarily absorb that pressure increase.

Proper use of an expansion tank can help avoid unnecessary opening of the pressure/temperature relief valve on a hot water heating tank or a hot water heating boiler.

The water pressure regulator can be adjusted to improve building water pressure and thus flow, by loosening a lock nut on the regulator and screwing the adjustment screw up or down a few turns.

Our photo (left) shows the water pressure regulator (photo bottom) and the regulator screw and lock-nut.

Be careful not to set the building water pressure too high, as you'll cause leaks.

For details on adjusting a municipal water pressure regulator
see How to Adjust the Water Pressure Regulator on Municipal Water Supply.

Watch out: don't set the water pressure reducing valve higher than necessary. Doing so wastes water and as we discuss
at WATER PRESSURE TOO HIGH: DANGERS, setting water pressure too high can cause both plumbing problems and actual serious safety hazards at buildings.

Causes of Variation in Building Water Pressure

As we discuss in more detail at WATER PRESSURE VARIATION CAUSES, there are several causes of variation in building water pressure:

  1. Number of plumbing fixtures being run at once
  2. Variation in municipal water delivery pressure
  3. Variation in small community water systems and private well pump water delivery pressure Details are
  4. Water pipe diameter, length, elbows and bends:
    See Definition of Static Water Pressure and Definition of Dynamic Water Pressure.
  5. Clogged water pipes reduce water flow rate, not water pressure.
  6. Variations in building occupancy levels

How do we Diagnose Poor Municipal Water Pressure & Flow in a Building - 5 Key Checks

Key things to check when water pressure and flow are inadequate in a building served by municipal water supply are

  1. The condition of individual plumbing fixtures, faucets, valves, and controls. A clogged sink or shower strainer will cause bad water pressure at individual fixtures while others may flow freely. A plumbing shutoff valve that is partly closed or clogged with debris will cause bad water flow at that fixture.
  2. The incoming municipal supply pressure. The municipal water supply source may be delivering water at low pressure.
  3. The condition of water piping between the building and the street water main. An older water supply pipe connecting the building to the water main in the street may be small in diameter, clogged with minerals, rust, or debris, or it could be leaking underground.
  4. The condition of building water supply piping. Clogged pipes due to minerals or rust, small diameter piping, long piping

    For details about the above items,
  5. The setting of the water pressure regulator at the building water meter or water shutoff valve. This topic is discussed just below.

Photograph of a water pressure regulator on municipal water supplyBad water pressure regulator or bad pressure regulator adjustment: (poor municipal water pressure) if the building is connected to a municipal water supply there may be a water pressure regulator installed, usually close to the water meter or where the water supply pipe enters the building. Photos of water pressure regulators and diagnosis and adjustment advice are

If the waer pressure control was set too low to start with or if there is a problem with the water pressure regulator, you may see an improvement in water pressure by diagnosing and adjusting or repairing this control.

If the loss of water pressure was sudden, it's not likely to be a problem the pressure regulator except in the less common cases of a blockage or failure in the regulator itself. In this photo our flashlight lights up a (rather amateurish looking) water pressure regulator installed on a municipal water supply.

You can see that a previous connection to the water meter was cut, left shut off (see that shutoff valve at the left hand vertical pipe - what happens if someone opens that valve?), and new fittings were installed to conduct incoming water to the building water supply piping.

The use of smaller diameter flexible copper tubing might restrict the incoming water flow, but the presence of a pressure regulator at all suggests that the incoming pressure may have been excessive. (Too high water pressure leads to fixture leaks.)

How to Adjust the Water Pressure Regulator or Pressure Reducing Valve on Municipal Water Supply

Details about how to adjust the building water pressure regulator or pressure reducing valve are found at WATER PRESSURE REGULATOR ADJUSTMENT. Excerpts are below.

We have already mentioned checking and adjusting the pressure control for the water pump on a private well system - just above. But what if the home does not have it's own well - what if the building is connected to a municipal water supply?

A water pressure regulator may be installed. See the illustration at the top of This article . A device, usually a few inches across and often shaped a bit like a bell, may be found installed at the water meter. The water meter is often installed where water pipes enter the building and the pressure regulator will be installed just after the water meter on the same pipe. You may see a screw secured by a lock-nut on the top of the meter or there may be another screw or knob that will permit the water pressure regulator to be adjusted to set the water pressure up or down in the building.

Which way to turn the water pressure regulator screw? On most pressure regulators, after loosening the lock-nut around the adjusting screw, turning the screw in will increase the water pressure. Don't overdo-it. Just a turn or two should make a difference. Keep track of the number of turns so that you can go back to where you started if necessary.

Sometimes the municipal water supply may itself be temporarily shut down or running at reduced flow. Check with your local water department or neighbors.

Increasing the building water pressure by adjusting the pressure regulator (or a pump pressure control switch) will not fix a poor water delivery rate from the source (municipal water main or local private water pump), but if the pressure was set too low to start with you may see an improvement by this adjustment. If your loss of water pressure or flow was sudden, it's not likely to be a problem with the pressure regulator except in the less common cases of a blockage or failure in the regulator itself.

Watch out: don't set the water pressure reducing valve higher than necessary. Doing so wastes water and as we discuss at WATER PRESSURE TOO HIGH: DANGERS, setting water pressure too high can cause both plumbing problems and actual serious safety hazards at buildings.

A Guide to Building Water Pressure by Adjusting or Repairing the Water Pump Pressure Control Switch on a Private Pump and Well Water Supply

For details about diagnosing poor well water pressure and flow, start at WELL WATER PRESSURE DIAGNOSIS or go directly to the individual items listed just below.

Water Pressure Diagnosis & Improvement Articles


Continue reading at WATER PRESSURE REDUCER / REGULATOR or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




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