Unless the context clearly requires otherwise, the following terms when used in this chapter shall be defined as follows:

(1) "Coordinated water system plan" means a plan for public water systems within a critical water supply service area which identifies the present and future needs of the systems and sets forth means for meeting those needs in the most efficient manner possible. Such a plan shall include provisions for subsequently updating the plan. In areas where more than one water system exists, a coordinated plan may consist of either: (a) A new plan developed for the area following its designation as a critical water supply service area; or (b) a compilation of compatible water system plans existing at the time of such designation and containing such supplementary provisions as are necessary to satisfy the requirements of this chapter. Any such coordinated plan must include provisions regarding: Future service area designations; assessment of the feasibility of shared source, transmission, and storage facilities; emergency inter-ties; design standards; and other concerns related to the construction and operation of the water system facilities.

(2) "Critical water supply service area" means a geographical area which is characterized by a proliferation of small, inadequate water systems, or by water supply problems which threaten the present or future water quality or reliability of service in such a manner that efficient and orderly development may best be achieved through coordinated planning by the water utilities in the area.

(3) "Public water system" means any system providing water intended for, or used for, human consumption or other domestic uses. It includes, but is not limited to, the source, treatment for purifying purposes only, storage, transmission, pumping, and distribution facilities where water is furnished to any community, or number of individuals, or is made available to the public for human consumption or domestic use, but excluding water systems serving one single-family residence. However, systems existing on September 21, 1977 which are owner operated and serve less than ten single-family residences or which serve only one industrial plant shall be excluded from this definition and the provisions of this chapter.

(4) "Purveyor" means any agency or subdivision of the state or any municipal corporation, firm, company, mutual or cooperative association, institution, partnership, or person or any other entity, that owns or operates for wholesale or retail service a public water system. It also means the authorized agents of any such entities.

(5) "Secretary" means the secretary of the department of health or the secretary's authorized representative.

(6) "Service area" means a specific geographical area serviced or for which service is planned by a purveyor.