The Reppisch flows in the Säuliamt (Affoltern district), canton of Zürich, an area featuring still partially untouched nature.

Between Birmensdorf and Dietikon, the river crosses a narrow valley which is used as a target range by the Swiss army troops stationed in the infantry barracks nearby.

Shortly before entering Dietikon, the river underruns the Mutschellenpassstrasse and the Bremgarten-Dietikon-Bahn railway.

In the spring of 1999, there were heavy floods in this area, blocking the road and the railway service for several days.

In addition there are 5 tributaries that are 2 kilometres long or more: the Dönibach, the Lättenbach, the Schwandenbach, the Tobelbach near Birmensdorf and the Malefizgraben, if one includes its right hand headstream, the Weidbach.