The term 'cross connection' in plumbing refers to:

The term 'cross connection' in plumbing specifically refers to a connection that allows drinking (potable) water to come in contact with non-potable water, particularly waste lines or sewage systems. This scenario poses a significant risk of contamination, as contaminants can flow back into the potable water supply due to negative pressure or backflow situations.

Understanding cross connections is critical for public health because they can lead to waterborne diseases and health hazards if not properly managed. Regulations and plumbing codes generally mandate the use of backflow prevention devices to protect potable water sources from such connections.

The other options, while they may describe some aspect of plumbing or water systems, do not accurately define a cross connection as recognized in public health and plumbing practices. A mutual exchange of water systems, temporary links of sewer lines, or overlaps between municipal and private systems do not specifically address the contamination risk inherent in cross connections.