The R.C. Harris Water Treatment Plant was named after Roland Caldwell Harris, the former Commissioner of Works for the City of Toronto from 1912 to 1945. The original plant, constructed in the 1930s, was designed to be expanded. It has since been enlarged and updated to continue serving as Toronto's largest water treatment facility, producing up to 47% of the city's water demands. The plant takes raw water from Lake Ontario and filters, disinfects, and treats it to provide safe drinking water for Toronto residents. It has been recognized as a nationally significant civil engineering site that has operated for over 70 years.