Water Pressure

Pressure Reducing Valve

Do you think about the water pressure in the plumbing system of your residential home or commercial building? Are you worried that the pressure is too high, or complain that the flow looks or feels too low? In southern California most homeowners and businesses are feeling the effects of water consumption limits and restrictions due to ongoing drought conditions. Therefore it is especially important to actively monitor and repair these systems to reduce or prevent property damage caused by leaks and flooding.

Here are some important ways to understand and maintain the water pressure in your home or building.

  1. Learn the locations of all valves in your plumbing system, and know how to operate them.
    • Meter service valve,
    • House or building cold main valve,
    • Water heater cold supply valve,
    • Hose valves,
    • Emergency fixture stop valves.
  2. Know the location of the Pressure Reducing Valve (PRV, pressure regulator, or regulator.) This device functions to reduce the service line water pressure to a safe operating pressure within the building system.
  3. What is the age of the PRV?
    • Average useful service life is 5-10 years.
    • Most are only warranted for 1 year by the manufacturer.
  4. What is the water pressure before and after the pressure reducing valve.
    • The service line pressure before the PRV is usually greater than 50 PSI. If the service line pressure exceeds 80 PSI then most regional plumbing codes require a PRV to be installed to reduce pressure to a safe level for use in the home or building.
    • If the service line pressure does not exceed 80 PSI over a 24-hour period, most regional plumbing codes do not require a PRV to be installed.
    • If the system pressure, as measured after the PRV (such as a back hose bib or at the water heater drain valve), is greater than the maximum setting of the PRV, then a test for thermal expansion should be performed before deciding that the PRV is failed.
      • Quick explanation: increasing water temperature causes water to expand (“thermal expansion”); heating water in a closed system causes pressure increase; pressure increase can stress the plumbing system and eventually cause premature failure.
    • If the system pressure, as measured after the PRV, is greater than the maximum setting of the installed PRV and thermal expansion is not a contributing factor, then the PRV may not be doing a good job anymore; the diaphragm may be worn out or other parts may be fouled with mineral buildup.
    • Most regional plumbing codes now require a thermal expansion tank to be installed when a system has a water heater installed downstream of the PRV.
      • Where a PRV is not already installed, the thermal expansion tank is usually not required. For example, if a building receives water service delivered at 55 PSI, a PRV is usually not required, hence a thermal expansion tank is also not required since a PRV is not present on the system.
    • Understand that your water pipe system is dynamic. It goes through changes everyday. Depending on the material that your system is made of, you may want to monitor your water pressure more frequently.
      • PEX water pipe has become a popular alternative to traditional copper water pipes due to the lower direct material costs. Consumers should be aware, however, that as a plastic material, PEX is susceptible to premature failure with excessive water temperature and pressure. Generally, as pressure increases the ability to convey water of excessive temperature without failure decreases. One positive benefit off PEX piping is that it does not corrode like copper pipe, and installation is generally easier due to weight differences between the materials.
      • Copper water pipe is very durable against excessive water pressure and temperature. Even so, the weakness of copper piping is that somewhere, over time, it will eventually corrode or erode, leak, and require repair or replacement. This is a natural and expected event, especially in the presence of aggressive, high mineral content water, or in soil of high or low pH level. But as a durable, traditional material against pressure and temperature, copper is the better performer vs PEX.

Water is a valuable resource and an essential component for healthy living. Monitor your plumbing system by checking the water pressure before and after the pressure reducing valve at least once per year. Understand the signs and effects of thermal expansion due to heating water. Plan for plumbing maintenance and get ahead of emergencies and nightmares caused by plumbing system neglect. Controlling water pressure is where it all starts.

Think Proactive. Be Proactive.

About the Author

Proactive Plumbing

Gas. Water. Sewer. "We do it all!"