This lead free anti-siphon vacuum breaker backflow preventer for hot or cold water prevents the reverse flow of polluted water from entering into the potable water supply due to backsiphonage. It consists of lead free construction, chemical resistant silicone seat disc, chrome hood, and an atmospheric vent to prevent spilling. It has a full size orifice to assure pipe size capacity and maximum flow. It is ideal for low flow, non-continuous hot or cold water health hazard applications such as on laboratory equipment.