What is necessary for high pressure sides of dishwashers?

The high-pressure sides of dishwashers require a check valve to ensure the proper functioning of the machine and to maintain hygiene standards. A check valve is a mechanical device that allows fluid (in this case, water) to flow in one direction only, preventing any backflow. This is especially important in commercial dishwashing systems where maintaining a high pressure is crucial for effective cleaning and sanitizing of dishes. The use of a check valve helps to avoid contamination of the clean water supply by preventing any dirty water from flowing back into the system, ensuring that the water used during the washing cycle remains sanitary.

The other options, while relevant in some contexts, do not serve this specific function. Back siphon refers to the backward flow of liquids, which is what the check valve helps prevent. Grey water pertains to reused wastewater from sinks and other non-toilet sources, which is not relevant to the high-pressure system. An atmospheric breaker is a device that helps in preventing backflow but is not as effective as a check valve in maintaining the pressure needed in dishwashers specifically.