Final answer:
A properly designed and installed sink typically has two air gaps: a high loop in the plumbing and an air gap device on the sink itself.
Step-by-step explanation:
A properly designed and installed sink typically has two air gaps. An air gap is a physical space between the water outlet and the receiving vessel, which prevents the backflow of contaminated water into the clean water supply. In the context of a sink, air gaps are commonly found in the form of a high loop in the plumbing under the sink and an air gap device on the sink itself.
The first air gap is created by the high loop in the plumbing. This is a section of the pipe that is raised higher than the sink drain. The high loop prevents wastewater from flowing back into the sink. The second air gap is the air gap device itself, which is a metal or plastic fitting installed on the sink deck or countertop. It creates a physical separation between the sink drain and the wastewater outlet, providing an extra layer of protection against backflow.