When is it necessary to utilize a reduced pressure zone (RPZ) assembly?

Utilizing a reduced pressure zone (RPZ) assembly is necessary in high hazard situations because these assemblies are designed to provide a high level of protection against backflow contamination. High hazard situations typically involve environments where a potable water supply could be contaminated with pollutants or pathogens, such as in industrial facilities, chemical plants, or laboratories. An RPZ assembly has two independently acting check valves and a pressure differential relief valve that ensures the water pressure in the system is maintained at a safe level, preventing any potentially contaminated water from flowing back into the public drinking water supply.

In contrast, other options refer to situations that do not warrant the use of an RPZ. For instance, low hazard situations may only require a less stringent backflow prevention method. Residential settings may also be classified as low to medium hazard, where simpler devices may suffice. Lastly, the use of a check valve alone does not establish the need for an RPZ assembly; they serve a different function and do not provide the same level of protection as an RPZ. Therefore, the correct identification of high hazard situations as requiring an RPZ assembly underscores its critical role in safeguarding public health.