where state is waterloo in canada?
Waterloo, Ontario. Waterloo is a city in Southern Ontario, Canada. It is the smallest of the three cities in the Regional Municipality of Waterloo (and previously in Waterloo County, Ontario), and is adjacent to the city of Kitchener. Kitchener and Waterloo are often jointly referred to as Kitchener-Waterloo, KW, the Twin Cities or the Tri-City.