Backflow may cause contamination of drinking water. Backflow may occur when which of the following is present?

Backflow occurs when water moves in the opposite direction than intended in a plumbing system, leading to a potential cross-contamination of safe drinking water. The presence of a cross connection—a link between potable water and non-potable sources—can significantly increase the risk of backflow. A cross connection typically happens when there is a physical connection between systems that should remain separate, such as mixing drinking water with wastewater or chemicals.

When there is a backflow due to a cross connection, contaminated water can flow back into the drinking water supply, creating serious health risks. Effective preventive measures, such as using backflow preventers, are essential in managing cross connections to maintain the integrity of the drinking water system.

Other factors like improper pipe sizing, low water pressure, and excessive water temperature can contribute to plumbing issues but are not direct causes of backflow in the same manner as cross connections. These issues primarily affect water flow and system efficiency without necessarily causing contaminants to enter the drinking water supply.