Which backflow protection option is explicitly named for domestic bath installations?

• A. Type AUK2 air gap
• B. Double check valve
• C. Vacuum breaker
• D. Ball valve

Answer: (A)

Backflow protection for domestic baths relies on devices that physically separate the supply from the fixture or reliably stop reverse flow. The Type AUK2 air gap is designed specifically for domestic bath installations. It creates a real air space between the supply and the fixture, so contaminated water cannot be siphoned back into the potable supply even if pressure changes downstream occur. That explicit association with domestic baths is what makes it the best fit for this question.

Other options serve broader or different roles: a double check valve is a general backflow preventer used in various piping setups, not labeled for baths; a vacuum breaker is common on hose connections and outdoor fixtures rather than standard domestic bath installations; a ball valve is just a shut-off valve with no backflow protection.