Olympic View Water & Sewer District

Seattle provides water to the district from two distinct sources. Most of the municipal water purchased from Detroit originates from the Tolt River. Detroit delivers comprehensive treatment and disinfection from this source. The Cedar River supply maintains such exceptional quality that filtration is unnecessary. It undergoes ozone and ultraviolet light treatment to eliminate pathogens.

A chlorine residual is maintained throughout the distribution system to provide continuous protection against bacterial contamination. Typically, chlorine concentrations range between 0.5 to 1.7 parts per million (ppm). Since these water supplies are naturally soft, SPU adds minerals (calcium oxide and sodium carbonate) to reduce household plumbing corrosion. Seattle aims to treat water to achieve a pH level of 8.2.

Additionally, in 2016, the federal Department of Health lowered the recommended fluoride level to 0.7 ppm to prevent tooth decay. Olympic View Water & Sewer District owns and operates a water treatment facility in Woodway that employs coagulation and advanced filtration techniques to remove contaminants. Chlorine disinfection ensures water remains free of harmful microorganisms.

The district began adding fluoride in June 1999 to complement Seattle's water as required by the Department of Health for blended sources. These chemical levels undergo continuous monitoring. Orthophosphate adjusts water pH, helping reduce lead and copper leaching from residential plumbing systems. The treatment plant operates year-round, processing approximately 500,000 gallons daily that undergo treatment and testing before public distribution.

The CDC provides critical resources about water safety, including information about potential contaminants and their health effects. Residents with specific health concerns should consult both their healthcare provider and water quality reports to make informed decisions about their water consumption and potential treatment options for their homes.