Waterbury is a city in the U.S. state of Connecticut. Waterbury had a population of 114,403 as of the 2020 Census. The city is 33 miles so…Waterbury is a city in the U.S. state of Connecticut. Waterbury had a population of 114,403 as of the 2020 Census. The city is 33 miles southwest of Hartford and 77 miles northeast of New York City. Waterbury is the largest city in the Naugatuck Valley Planning Region and second-largest city in New Haven County.