What is the key requirement concerning indirect discharges?

The key requirement concerning indirect discharges is that there must be no physical connection between the waste line and drain. This is crucial for preventing the contamination of potable water supplies. An indirect discharge is designed to ensure that wastewater does not backflow into the drinking water system. By maintaining a physical separation, the risk of cross-contamination is minimized, ensuring that the health and safety of the water supply are protected.

The other options do not align with the primary health and safety objective that governs indirect discharges. For instance, a physical connection to the waste line would defeat the purpose of maintaining separation. Similarly, requiring direct and visible discharges or a constant flow does not focus on the essential need for preventing contamination through physical barriers. Thus, the emphasis on maintaining no physical connection is fundamental to safeguarding water quality.