What is the function of the backflow preventer?

The primary function of a backflow preventer is to ensure that water from the internal system does not unintentionally flow back into the municipal or city water supply. This device is crucial for maintaining the integrity and safety of the community's drinking water. If contaminated water from a facility were to reverse flow into the public water supply, it could pose severe health risks. Therefore, the backflow preventer acts as a safeguard, stopping any reverse flow and protecting the overall water quality for all users in the system.

Other options provided do not align with the primary role of a backflow preventer. Increasing water pressure and filtering contaminants are functions served by other types of plumbing equipment, while monitoring water quality is the responsibility of water treatment facilities and monitoring systems, not the backflow preventer itself.