What should water supply lines and fittings prevent from occurring?

Water supply lines and fittings must be designed to prevent backflow, which is an essential consideration for maintaining safe drinking water. Backflow occurs when water flows in the opposite direction from its intended path, potentially allowing contaminants to enter the clean water supply. This can happen due to various conditions, such as changes in pressure within the plumbing system, and can lead to serious health risks.

To safeguard against this risk, plumbing systems typically incorporate devices such as check valves and backflow preventers. These devices ensure that water only flows in the desired direction, effectively isolating the potable water supply from potential sources of pollution.

While preventing leakage, corrosion, and contamination are also important aspects of maintaining a water supply system, the specific focus here is on the prevention of backflow, as it directly relates to the protection of public health and safety.