The Auer (also called Mühlbach or Ziegelbach) is a river in Hesse, Germany which springs from the western edge of the Felsberg in the Hessian Odenwald between Balkhausen and Bensheim-Hochstädten.

[2] Like at the antetype Freiburg Bächle, an ever constant part of the Auer flows openly through the Bachgasse, through the old village of Auerbach passing numerous half-timbered buildings towards the Bundesstraße 3 (Darmstädter Straße).

After the two streams united again, the Auer crosses the Bundesstraße underground and flows towards the Auerbach railway station.

[3] After crossing the railway line Darmstadt-Heidelberg, the Auer reaches after approximately 1 km its mouth.

It flows into the Winkelbach coming from Bensheim, which is called upstream of the Auer's mouth Lauter.