The Oderteich is an historic reservoir about seven kilometres northeast of Sankt Andreasberg in the Upper Harz in central Germany. It was built by miners from St. Andreasberg in the years 1715 to 1722 and, today, is an important component of the water supply network known as the Upper Harz Water Regale. Moreover, for 170 years, from the time it was completed to the end of the 19th century, the Oderteich had the largest dam in Germany. The dam lies at a height of 725 m above NN by the B 242 federal highway, about a kilometre west of its intersection with the B 4.

Sankt Andreasberg is a former town in the district of Goslar, in Lower Saxony, Germany. Since 1 November 2011, it is part of the town Braunlage. It is situated in the Harz, approximately 7 km west of Braunlage proper, and 20 km east of Osterode am Harz.