Which type of structure typically requires an RPZ backflow preventor?

An RPZ (Reduced Pressure Zone) backflow preventer is specifically designed to protect against backflow, which can occur when there is a drop in water pressure. This type of device is especially necessary in scenarios where the risk of contamination is higher due to the ongoing use of varying water pressures, as is commonly found in high-rise buildings.

In high-rise buildings, water needs to be pumped to various floors, which can create conditions where backpressure could potentially draw contaminated water from lower systems back into the potable water supply. The RPZ backflow preventer is engineered to handle large fluctuations in pressure and prevent any backflow that may contaminate the drinking water supply.

In contrast, smaller structures such as homes, schools, or swimming pools generally do not face the same level of backpressure risks and complexities that high-rise buildings do. Thus, they might not require an RPZ backflow preventer as a standard practice, making it clear why high-rise buildings are the correct choice for this situation.