Which of the following is included in cross-connection controls?

Cross-connection controls are critical components in maintaining a safe and contaminant-free water supply. They are designed to prevent the backflow of potentially contaminated water into the public water system. Indirect waste piping is included in cross-connection controls because it is specifically engineered to ensure that wastewater does not directly connect with potable water systems, thereby preventing any potential backflow of contaminants into drinking water.

Indirect waste piping allows for a safe route for waste to drain into the sewage system while separating it from drinking water supplies, thus acting as a critical barrier against contamination. This system is essential for facilities where food and beverages are prepared, as it helps maintain hygiene and safety standards.

The other options, while they have their respective roles in plumbing and water management, do not serve the specific purpose of preventing backflow in the same manner as indirect waste piping. Water meters, gate valves, and air vents primarily focus on regulating water flow and pressure but do not directly address the risks associated with cross-connections.