There are three types of public water systems: Group A, Group B and Two-Party. A Group A system is the largest type of system. Any system with more than 15 connections or that serves 25 or more individuals for 60 or more days per year is considered a Group A public water system. All Group A systems are regulated by the State Department of Health Office of Drinking Water. Mason County Public Health regulates all Group B Water Systems in Mason County. A Group B water system serves more than 1 and less than 15 connections AND less than 25 individuals per day. The regulations governing public water systems are Washington Administrative Code (WAC) 246-290 for Group A systems and WAC 246-291 for Group B systems. These regulations can be found at the following web site: Department of Health. Setbacks for Group A and Group B wells are available under the links to the left. Group B water system approval is explained under the “Group B packet” link to the left. Group A water system approval must be obtained through the State Department of Health Office of Drinking Water (see the link earlier in this paragraph). A County Well Site Inspection is required for Group A water system approval (see link on left).

The Two-Party water system serves two single-family residences. The process for obtaining approval of a two-party water system can be found under the “Two Party Packet” link to the left of this page. While a two-party water system is technically a public water supply, the rules have been changed to aid in the approval process. The setbacks for a two-party well are the same as the individual well setbacks (see the link to the left).