Which scenario represents a cross-connection risk?

• A. A garden hose connected from potable water to a faucet.
• B. A garden hose connected from a non-potable source to a faucet.
• C. A fixed connection between potable water and non-potable water with backflow preventer.
• D. A potable water line connected to an irrigation system with proper backflow control.

Answer: (B)

A cross-connection occurs when a link between potable water and a non-potable source could allow contaminants to flow back into the drinking-water system. The garden hose scenario that connects a non-potable source to a faucet creates exactly that risk: if pressure changes or a siphon forms, non-potable water can be drawn into the potable supply through the hose and faucet, potentially contaminating the drinking water. The other situations either involve only potable connections or include backflow protection, which prevents such backflow. A simple potable-to-faucet hose isn’t a cross-connection risk by itself, but a fixed potable-to-non-potable connection with a backflow preventer is protected against backflow, and a potable line with an irrigation system and proper backflow control has safeguards too.