Three Different Types of Reduced Pressure Zones — Which One Meets Your Needs?

RPZ backflow preventerReduced pressure zones (RPZ) are the most complex but most secure and reliable backflow prevention devices. The primary benefit is the relief valve alerts you if anything in the system is out of order. This provides maximum protection because you always know if your water supply is being properly protected.

RPZs are designed for use in continuous pressure applications that are subject to back-pressure or back-siphonage incidents and health hazard cross-connections. Examples include containment at the main service line entrance, commercial boilers, hospital and laboratory equipment, waste digesters, and car washes. An RPZ assembly consists of an inlet shutoff valve, two independently operating spring-loaded check valves separated by a pressure differential relief valve, four test cocks, and an outlet shutoff valve.

Backflow preventers are commonly installed in buildings where clean water cross-connects with any of the following installations:

  • Irrigation systems: Backflow from irrigation systems and extensive lawn sprinkler systems are hazardous due to fertilizers and lawn chemicals, like pesticides.
  • Fire suppression systems: Create pressure differences and siphoning effects that can lead to backflow.
  • Large boilers: Presents a backflow hazard when the pressure inside gets too high. It then pushes the dirty water back up into the clean water system.

An emerging trend in backflow prevention across the country is to ONLY use RPZs on domestic and fire lines to deliver the following benefits:

●        The best protection against any form of backflow

●        Fail-safe device to protect the water supply

●        Protect the water supply regardless of "hazard" designation

●        RPZs alert you to any problems within the system

There are several different types of RPZs. Three main companies supply the majority of RPZs, including Watts, Wilkins/Zurn, and Apollo.


A global leader of quality water solutions for residential, industrial, municipal, and commercial settings. Its family of brands offers one of the most varied product lines in the world, with world-class, water-related solutions focused on drainage, HVAC and hot water, plumbing and flow control, and water quality and rainwater harvesting. The global research and development and manufacturing teams are constantly creating high-quality products for customers all over the world.


Zurn Industries, LLC, is a recognized leader in the commercial plumbing products market, including specialties in municipal, healthcare, and industrial markets. Zurn offers the widest breadth of engineered water solutions, including a wide spectrum of sustainable plumbing products. Zurn delivers total building solutions for new construction and retrofit applications that enhance any building’s environment. They manufacture the industry spectrum of advanced water solutions to save customers steps, cost of ownership, and labor.


Apollo Valves produces American-made backflow prevention devices that offer ease of maintenance. They process superior drop ratings and are completely constructed and assembled in the United States. Apollo offers fire protection, as well as waterworks, irrigation and plumbing.

Here is how the three companies’ RPZs compare to each other:



USC Approved

Location Made


Largest market share, longest market tenure




Innovative designs, lower life cycle costs




Simple designs, ease of maintenance




Best Practices in Backflow Prevention & Protection

Topics: RPZ Flooding

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