The Seattle Public Utilities water system provides direct water service to around 630,000 people in and just outside the City of Seattle and sells water wholesale to cities and water districts serving another 720,000 people. Seattle's publicly owned water system began in 1890 with the purchase of several private water companies. Creation of a gravity supply system from the Cedar River beginning in 1901 gave Seattle enough water to accommodate its own growth and supply an ever-increasing number of other jurisdictions. Inauguration of the South Fork Tolt River supply in the 1960s added a second source, ensuring adequate supplies well into the twenty-first century. As the system grew and water quality requirements increased, water treatment evolved from manual application of chlorine at intakes to the current sophisticated Tolt and Cedar River treatment facilities. This slideshow history of the Seattle water system was written and curated by Kit Oldham.