What is the minimum air gap required for lavatories not affected by sidewalls with an opening no more than 13 mm?

The minimum air gap required for lavatories not affected by sidewalls with an opening no more than 13 mm is established to ensure proper drainage and prevent back-siphonage, which could lead to contamination of the water supply. An air gap serves as a physical separation between the potable water supply and potential pollutants or contaminants, effectively maintaining water quality and safety.

In this case, the standard specifies an air gap of 25 mm, which is considered sufficient to prevent any backflow or mingling of wastewater with the clean water supply. This regulation is in place to safeguard public health and ensure that sanitation systems function effectively.

The other measurements like 1 inch (which is approximately 25.4 mm), 38 mm, and 50 mm do not align with the specific requirements for this scenario, as they exceed the minimum air gap necessary for lavatories without sidewall interference. Adhering to the correct air gap measurement is crucial for compliance with plumbing codes and health regulations.