(1) The rules of this chapter apply to a Group B public water system that provides drinking water to fewer than fifteen service connections and:

(a) Fewer than twenty-five people per day; or

(b) Twenty-five or more people per day for fewer than sixty days per year, provided the system does not serve one thousand or more people for two or more consecutive days.

(2) The rules of this chapter do not apply to a Group B system that:

(a) Consists only of distribution or storage facilities and does not have any source or treatment facilities;

(b) Obtains all water from, but is not owned by, a public water system where the rules of this chapter or chapter 246-290 WAC apply; and

(c) Does not sell water directly to any person.

(3) The rules of this chapter do not apply to a Group B system that provides water to one or two service connections, except:

(a) In a county in which a local board of health has adopted requirements for Group B systems with one or two service connections; or

(b) When the department determines that it is necessary to protect public health and safety, such as if the system serves a connection with a use listed under WAC 246-291-010 (62)(a) through (h).

(4) A proposed Group B system shall meet planning, engineering, and design requirements under WAC 246-290-100 through 246-290-250 if:

(a) The design submitted under WAC 246-291-120 proposes to supply water to another public water system and the combined number of service connections or total population served meets the definition of a Group A public water system; or

(b) The proposed system is being designed to serve ten to fourteen residential service connections using average household population standards as required under WAC 246-291-200(2).