Why is a backflow preventer required in many sprinkler systems?

• A. To prevent contaminated water from flowing back into the public water supply (back-siphonage).
• B. To enhance filtration of water entering the system.
• C. To reduce water hammer in the main supply.
• D. To regulate the pressure in the building.

Answer: (A)

Backflow preventers are required because sprinkler systems tie into the public potable water supply. If pressure drops or a cross-connection occurs, water from the sprinkler system could be drawn back into the drinking water, potentially carrying contaminants from the building. The backflow preventer stops any reverse flow, protecting the public water supply from back-siphonage.

The other options don’t fit because filtration, while useful for particulates, doesn’t stop reverse flow; reducing water hammer is handled by other devices and methods, not a backflow preventer; and pressure regulation is done with pressure-reducing valves, not backflow prevention.