When should backflow prevention devices be installed in water systems?

Backflow prevention devices are critical components in maintaining the integrity and safety of water systems. Their primary function is to prevent the reverse flow of water, which can introduce contaminants into the potable water supply. The correct answer highlights the importance of these devices whenever chemicals are introduced into the water system.

When chemicals are added, either for treatment processes or any other purpose, there is a significant risk of those substances inadvertently flowing back into the drinking water. This could occur due to changes in pressure within the system, and without proper prevention methods in place, health risks pose a danger to consumers. Therefore, the installation of backflow prevention devices becomes essential in scenarios where chemicals are present, as they act as a safeguard against potential contamination.

In addition to situations involving chemicals, there are also other circumstances that warrant the use of backflow prevention devices, such as changes in system pressure, cross-connection points, and specific system configurations. However, the context of chemical introduction is particularly crucial due to the direct implications for human safety and public health.