What type of sewer serves multiple buildings and is not regulated by public authorities?

The correct answer is private sewer. A private sewer is a system that serves multiple buildings or properties but is owned and maintained by the property owners rather than a public authority. This distinction is significant because it means that the responsibilities for maintenance, repairs, and compliance with local plumbing codes lie with the private entities rather than the municipality or public utility.

In many cases, private sewers can be found in developments that do not connect to the public sewer system or in properties that are situated in rural areas. These systems may face different regulations compared to public sewers, which must meet stricter public health and safety codes overseen by government entities.

Public sewer systems, by contrast, are managed and maintained by governmental agencies, ensuring that local standards are met and allowing for broader public health protections. Common sewers and municipal sewers generally imply some level of public oversight and regulation, distinguishing them from private systems.