What requirement must be met for discharge pipes from a water distribution system?

The requirement for discharge pipes from a water distribution system to discharge by means of an air gap is crucial for maintaining sanitary conditions and preventing contamination of the potable water supply. An air gap creates a physical separation between the end of the discharge pipe and the water level in the receiving vessel, such as a sink or tank, ensuring that no backflow can occur. This is particularly important in preventing wastewater from entering clean water systems, which could lead to health hazards.

In plumbing code compliance, the air gap serves as a vital barrier that eliminates the risk of siphoning any contaminated water back into the clean drinking water system, thus protecting public health. Thus, discharging through an air gap is a fundamental plumbing principle designed to safeguard the water supply from contamination.

Other requirements, such as ensuring pipes have a constant slope for drainage or providing insulation, relate to the efficient function of the plumbing system but do not specifically address contamination prevention in the same critical manner as the air gap. Discharging directly into storm drains is generally not permitted for water distribution systems due to the risk of contamination and does not meet the standard sanitary practices required in plumbing codes.