Waterville is a city in Marshall County, Kansas, United States. As of the 2020 census, the population of the city was 658. Waterville was foun…Waterville is a city in Marshall County, Kansas, United States. As of the 2020 census, the population of the city was 658. Waterville was founded in 1868 by the railroad company. It was named after Waterville, Maine, the hometown of a railroad official.