Tarentum is a borough in Allegheny County in the U.S. state of Pennsylvania. It is 22 miles (35 km) northeast of Pittsburgh, along the Allegheny River. Formerly an industrial center, plate glass and bottles were manufactured here; other products were bricks, lumber, steel and iron novelties, steel billets and sheets, sack and wrapping paper. The Pennsylvania Railroad operated a station in Tarentum; its rail line ran through the town. The population was 4,993 at the 2000 census.
Tarentum is located at 40°36′11″N 79°45′20″W / 40.60306°N 79.75556°W / 40.60306; -79.75556 (40.603042, -79.755447).
According to the United States Census Bureau, the borough has a total area of 1.4 square miles (3.7 km²), of which, 1.2 square miles (3.2 km²) of it is land and 0.2 square miles (0.4 km²) of it (12.06%) is water.