Watertown is a town in Litchfield County, Connecticut, United States. The population was 22,514 at the 2010 census. The zip code for Watertown is 06795. It is a suburb of Waterbury. It borders the towns of Woodbury, Middlebury, Morris, Plymouth, Bethlehem, and Thomaston. The urban center of the town is the Watertown census-designated place, with a population of 3,574 at the 2010 census.