This reduced pressure zone assembly, 1 1/2 inch, with its exclusive design incorporates the patented air-in and water-out principle for protection during an emergency condition preventing the flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure in accordance with national plumbing codes and water authority requirements. It is ideal for protection in continuous pressure piping applications and at cross-connections identified as health hazards and from other contaminants found at the service line entrance. Its compact modular design facilitates easy maintenance for in-line repairs. It can be installed horizontal or vertical without the need of any special tools. This assembly consists of a lead free silicon bronze body, quarter turn ball valve shutoffs with lever handles, check modules, replaceable seats, top mounted test cocks, and a pressure differential relief valve.