Where Do You Get Your Drinking Water?

Private and Public Systems

County citizens receive potable water from a variety of sources. These sources are classified as either private or public water systems. Private water systems serve only a single connection and usually consist of a well used for a single home. There are approximately 12,000 private water systems in King County.

Public water systems contain more than one connection. The public systems are managed by

• homeowners;
• private, non-profit organizations and corporations such as homeowners' associations;
• private, for-profit companies;
• municipalities such as cities and water districts.

Public water systems are further classified by size. A public water system is classified as a Group B system if, in general, it serves from 2 to 14 connections. About 1,700 Group B public water systems currently operate in King County. In general, a Group A system serves 15 or more connections. There are 217 Group A public water systems in the county. There are also other characteristics that differentiate Group A and Group B systems.

Most Citizens Served By Seattle Public Utilities

The City of Seattle, through the Seattle Public Utilities, provides potable water for approximately 1,300,000 people, either through direct service or the sale of water to 27 other water utilities. The remaining King County population, about 400,000 people, obtains their potable water from approximately 14,000 other public and private systems. The reason for the tremendous number of water systems with small numbers of connections is largely historical. At the time when many of these systems were developed there were no other viable options for water service. Over time, a regional network of inter-connected systems has been developed in many parts of the county. Although the regional network is not complete, many areas of the county can now be served without the need to form new water systems. The number of water systems has been decreasing recently and will likely continue to do so as smaller systems are consolidated into larger ones. Further information about who provides water in the county is contained on a map of the larger water utilities and graphs showing the sizes of the utilities and populations served.

Click on the graph to see an enlargement.

Population Served by Water System Type depicts the market share of various water systems in King County.

King County Regulatory Role in Water Supply 

King County is not a water utility and does not supply potable water to citizens. Instead, King County has certain regulatory authority for Group A and Group B water systems that operate in unincorporated King County. The Seattle-King County Department of Public Health must approve any construction for small Group B systems (from 2 to 9 connections) and review required water quality test results.

Several state agencies also have a role in regulating water utilities. The Washington State Department of Ecology issues water rights, which allow waters of the state (surface and ground water) to be appropriated for public benefit. A water right is required for any water utility with 7 or more connections. The Washington State Department of Health regulates drinking water quality for Group A systems and Group B systems with 10 to 14 connections.

Group A systems that are expanding are required to prepare water system comprehensive plans every six years for approval by the Washington State Department of Health. If those Group A systems operate in unincorporated King County, the plans are also required to be approved by King County. The King County approval process consists of two steps, (1) review of the comprehensive plan by the Utilities Technical Review Committee, an inter-departmental staff group, and (2) approval by ordinance by the Metropolitan King County Council and King County Executive.

In addition, if a water system operates in the right-of-way of a King County road (i.e., if a system's water main runs along the road), then a franchise is required. A franchise is an agreement between King County and the water system stipulating the conditions that must be met by the water system in order for it to operate in King County right-of-way. The county must approve any construction work proposed by a franchised utility in King County right-of-way. To find out more about franchises in King County, please visit the Web site for King County's Permits and Franchise Unit, Property Services Division.

Water and the King County Permitting Process

If your property is in unincorporated King County and you want to undertake development activity, you will need to obtain approval from the King County Department of Development and Environmental Services (DDES). DDES will coordinate review of applications for building permits, subdivisions, rezones, and lot line adjustments and will require information demonstrating that water is available to serve the property. If you are proposing to obtain water from a private water system (a well connected to a single home), you will need at least five acres of property located in a Rural-designated area (as opposed to inside the Urban Growth Boundary). A private water system on five acres of property is allowed within the Urban-designated area only if public water cannot be provided in a timely and reasonable manner. However, any property owner receiving permission to put a private system in an Urban area must agree to connect to a public water system when public water is available. In all cases, you will need approval of the private well from the Seattle-King County Department of Public Health.

If you are proposing to obtain water from a public water system, then you need to obtain a certificate of water availability from the public water system. The certificate demonstrates that the public water system has water available to serve the new connection or connections being proposed. Sometimes a public water system is limited in its ability to provide water to new connections because of supply, water right or infrastructure limitations. In such cases, the water system may declare a moratorium on new connections and may not issue new certificates of water availability. Several water utilities in the county have declared moratoria over the past several years, including Covington Water District, King County Water District 111, Sammamish Plateau Water and Sewer District, and King County Water District 19. As the population of this region increases and more demands are put on the regional water supplies, more water systems may declare moratoria.

Do We Have Enough Water?

King County is currently working with water utilities throughout the county as well as those in Pierce and Snohomish counties to assess regional water demands and supply sources and determine how the region may best meet its future water needs. Part of the ongoing regional discussion will focus on instream flows -- the amount of water needed to allow continued viability of organisms utilizing our rivers, streams, lakes and wetlands, most notably salmon. The National Marine Fisheries Service has listed the Puget Sound chinook salmon as threatened. This Endangered Species Act listing will greatly affect our future decisions about water supply.

In general, most of the time this region has plenty of water available. During the summer, however, water use increases from 50 to 250 percent because of irrigation of lawns, golf courses, and parks. Accommodating this "peak" demand is one challenge for regional water utilities. Utilizing water stored in tanks and reservoirs can meet this demand over the short term. During the early fall, however, when reservoir levels are low due to low flows in streams and rivers, and the rainy season has not yet started, the water needs of people and migrating salmon can conflict. Accommodating this summer peak demand and managing instream flows during the critical early fall period are the issues driving the current multi-county discussion.

This graph shows average water use by Seattle retail and wholesale customers for water years 1990 through 1998, except for the drought year of 1992. The graph also shows average precipitation as measured by the National Weather Service gage at SeaTac airport between 1948 and 1994.

What Can Be Done?

The easiest and most cost-effective means of extending the current water supply is to use less water, particularly during the summer. Conservation can be achieved through installation of water saving devices on faucets and toilets, selection of water-efficient appliances, changes in lawn watering practices, and modifications to personal behavior (like keeping the water off when brushing your teeth).

In addition to evaluating the feasibility of more withdrawals from existing sources or new sources of water, another option is to use additional water quality treatment to reclaim some of the wastewater produced in the region. This reclaimed water is currently being used in several demonstration projects locally and has been used successfully for years in other parts of the country for irrigation, industrial, and other non-potable uses. Using reclaimed water for non-potable uses lessens the demand on our potable water supplies. King County is currently working in the region to promote the use of reclaimed water when feasible.