Final answer:
The potable water supply to the aspirator should be protected by a backflow preventer to prevent contamination of the water supply.
Step-by-step explanation:
A potable water supply to the aspirator should be protected by a device that prevents the undesirable reverse flow of water, which could contain contaminants, from entering the clean water supply. This is critical in maintaining the quality of drinking water and for overall public health safety.
The correct answer to what should protect the potable water supply to the aspirator is a backflow preventer. This device is specifically designed to keep potable water from being contaminated by preventing water from flowing back into the main water supply if a pressure drop occurs. It is an essential component in many plumbing systems where there is a risk of contaminating the potable water.
Other options, such as a check valve, pressure relief valve, and flow control valve, have different functions and are not specifically designed to prevent backflow contamination. A check valve allows flow in one direction but closes automatically to prevent flow in the reverse direction. A pressure relief valve is designed to protect a system against overpressure by releasing excess pressure. A flow control valve regulates the flow rate of water in a specific portion of the plumbing system.