What do plumbing codes regulate in the context of ICC?

Plumbing codes are specific regulations that govern the installation and maintenance of plumbing systems to ensure safety, functionality, and public health. These codes outline the required standards for piping, fixtures, water supply, waste disposal, and other plumbing-related systems. Compliance with these codes helps prevent issues such as contamination of the water supply, sewer overflows, and improper drainage, which can pose significant health risks to the population.

The other options encompass different areas of building codes and regulations. The construction of exterior walls pertains to structural integrity and materials used in building design, while the usage of fire-retardant materials relates to fire safety standards. The design of mechanical systems involves regulations related to heating, ventilation, and air conditioning (HVAC) systems, which are distinct from plumbing systems. Therefore, the regulation of plumbing systems is uniquely covered under specific plumbing codes, which is why the first choice is the most appropriate in this context.