The Ruwer is a river in Germany with a length of 46 kilometres (29 mi). It is a right tributary of the Moselle. The valley of the Ruwer is a part of the Moselle wine-growing region near Trier in the state of Rhineland-Palatinate. It is famous for its Riesling wines, see Ruwer (region), and, prior to 1 August 2007, the Moselle region used to be known as Moselle-Saar-Ruwer.
In the lower Ruwer valley are the villages of Waldrach, Kasel, Mertesdorf, Eitelsbach and Ruwer.
The Roman city of Trier (Augusta Treverorum) was supplied with water by the Roman Ruwer Aquaduct, which delivered up to 25,000 cubic metres per day.
In A.D. 371, the Ruwer was mentioned by the Roman poet, Ausonius, in his poem, Mosella as follows: "The Ruwer turns the corn-grinding millstones in giddy whirls and draws the shrieking saws through smooth marble blocks."
Other tributaries of the Ruwer include the Apfelbach, Borgraben, Eitelsbach, Gusterather Waschbach, Kundelbach, Labach, Moertschelbach, Rimperterbach, Wenigbach, Wenzelbach and the Wilzenburger Waschbach.