What is the purpose of a backflow preventer?

The purpose of a backflow preventer is to prevent contamination of the water supply. This device is essential in protecting drinking water from being contaminated by reverse flow, which can occur when there is a change in pressure in the water supply system. For instance, if the pressure drops in the main water line, it can create a vacuum that may draw potentially contaminated water from irrigation systems, sinks, or other sources back into the clean water supply.

Backflow preventers work by allowing water to flow in one direction only, ensuring that contaminants do not re-enter the potable water system from other plumbing fixtures. This is particularly important in landscaping and irrigation systems where fertilizers, chemicals, or pathogens may be present in the water used for irrigation. Installing a backflow preventer is not just a best practice, but often a legal requirement to safeguard public health.

The other options, while related to water systems, do not encapsulate the primary function of a backflow preventer. Regulating pressure is typically managed by pressure regulators, measuring water usage involves flow meters or similar devices, and filtering sediment is the role of filtration systems, all of which serve different purposes in the context of water management.