King County, Washington — public water systems

How does King County compare with other Washington counties?

King County has the 8th-most active public water systems among the 72 counties listed for active Washington systems in EPA records; among the 44 with 3 or more systems, the median has 75. Its systems report 3,321,960 people served in total, the largest county figure in the state and 33% of the statewide total. The average system here reports serving 15,523 people, about 7.1 times the Washington average of 2,172. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.

Where does King County's drinking water come from?

By primary water source, King County's active systems draw on groundwater (172, 80%), purchased surface water (33, 15%), surface water (6, 2.8%) and purchased groundwater (3, 1.4%). Overall, 82% rely mainly on groundwater (including purchased groundwater) and 18% on surface water, compared with 94% and 5.7% across Washington. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Seattle Public Utilities, draws primarily on surface water.

What kinds of water systems operate in King County?

King County's active systems break down as 153 community systems (71%), 13 non-transient non-community systems (6.1%) and 48 transient non-community systems (22%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as private (66%), local government (27%), federal government (3.7%) and state government (2.8%).