This 3/4 inch lead free reduced pressure zone backflow preventer assembly with its exclusive design incorporating the patented air-in and water-out principle for protection during an emergency condition prevents 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. 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. 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. This assembly consists of a lead free bronze body, quarter turn ball valve shutoffs with tee handles, stainless steel check modules for hot and harsh water conditions, replaceable seats, top mounted test cocks, and a pressure differential relief valve.