The department will issue an approval and a certification of necessity to an applicant water district if all of the following conditions are satisfied:

(1) The granting of an approval and a certification of necessity will eliminate or alleviate an existing or imminent health problem as determined by the department.

(2) A sewer system does not exist in a substantial portion of the proposed service area and no regularly constituted and established sewer entity intends to construct and operate a sewer system in a substantial portion of the proposed service area within the reasonably foreseeable future.

(3) The proposed service area conforms to any or all established sewage drainage basins designated pursuant to RCW 90.48.270.

(4) The proposed service area conforms to any or all established comprehensive plans for sewage drainage basins, established pursuant to RCW 90.48.280.