Which backflow prevention device protects against back pressure?

The double check-valve assembly is specifically designed to protect against both backpressure and backsiphonage. This device consists of two independently acting check valves, which provide an effective barrier to prevent the reverse flow of contaminated water into the potable water supply.

When there is backpressure, which can occur due to various reasons such as a rise in water pressure in the system or even when there are pumps involved, the double check-valve assembly ensures that the water flows only in one direction and any potential contaminants are kept from entering the clean water supply.

This makes it particularly useful in protecting against non-health hazards where there might be a concern about chemicals or other non-toxic substances contaminating the water supply. In contrast, the other options may have limitations with regard to their specific applications or types of backflow they address, making the double check-valve assembly the most suitable choice for preventing backpressure problems.