Waterville is a city of 1,800 people in southeastern Quebec, Canada, in the Coaticook Regional County Municipality. Prior to January 1, 2002, it …Waterville is a city of 1,800 people in southeastern Quebec, Canada, in the Coaticook Regional County Municipality. Prior to January 1, 2002, it was in La Région-Sherbrookoise Regional County Municipality, and was the only member of that RCM that did not amalgamate into the expanded city of Sherbrooke on that date.