(1) A purveyor of a Group B system shall provide potable water to the system's consumers.

(2) The department or health officer may require a purveyor to collect water quality samples, have the samples analyzed by a certified lab, and report results as required under WAC 246-291-360, when the department or health officer:

(a) Determines a public health risk exists;

(b) Receives information documenting contamination;

(c) Receives a report of suspected or known waterborne illness from a health care provider as required under chapter 246-101 WAC; or

(d) Is aware of, or observes, a situation in which the source may be vulnerable to contamination. For example, a source is vulnerable to contamination from a flood event.