Colpach-Bas (Luxembourgish: Nidderkolpech, German: Niedercolpach) is a village in the commune of Ell, in western Luxembourg. As of 2001[update], the village has a population of 105.
Colpach Castle dates from the beginning of the 14th century when it was a stronghold. It was adapted as a manor house in the 18th century. Today it is a convalescent centre run by the Red Cross.
Coordinates: 49°45′N 5°50′E / 49.750°N 5.833°E