Which of the following best describes an installer of OSSF systems?

The description of an installer of On-Site Sewage Facilities (OSSF) systems is best captured by the notion of a business entity constructing sewage facilities. An installer is responsible for the physical assembly and installation of various components of the sewage treatment systems, ensuring they are set up according to design specifications and regulatory standards. This role involves the hands-on work required to bring the system into operation.

In this context, it's important to differentiate between other roles related to OSSF systems. For instance, a person conducting inspections plays a crucial role in assessing compliance and functionality but is not directly involved in the installation process. Similarly, a governmental regulator oversees compliance with environmental laws and regulations but does not engage in the direct installation of sewage systems. A system designer focuses on planning and creating the design blueprint for the sewage facility rather than the actual installation.

Thus, the role of the installer is distinctly aligned with the construction aspect of OSSF systems, making the description of a business entity constructing sewage facilities the best fit.