What is a key characteristic of a public water system?

A key characteristic of a public water system is that it serves at least 25 people or has a minimum of 15 service connections. This definition helps delineate between public and private water systems, ensuring that those who rely on the system for drinking water are adequately provided for in terms of quality and reliability. Public water systems are subject to specific regulations to ensure water safety and compliance with health standards, particularly because they serve a larger population.

The other options do not accurately capture the nature of a public water system. A private company may regulate some public systems, but a significant number of them are maintained by public or government entities. Additionally, a public water system does not have to serve the same residents year-round, as transient populations can also utilize these systems. Lastly, while providing potable water is crucial, it is not the defining characteristic of a public water system, as such systems must meet certain thresholds regarding the number of people served, rather than focusing solely on the quality of the water supplied.