Sewell is an unincorporated area within Mantua Township in Gloucester County, New Jersey, United States. Sewell also refers to part of Washington Township, which is not part of Mantua Township. Locals refer to the Sewell part of Mantua as Old Sewell. The area is served as United States Postal Service ZIP code 08080. As of the United States 2000 Census, the population for ZIP Code Tabulation Area 08080 was 36,410.