It has its source at the homestead "Heimliswald" in the district Rötenberg of Aichhalden at an elevation of 699 m above sea level and flows first in southeast direction.

After the Eschach has limited the Winzeln-Schramberg Airfield to the west - the municipal area of Fluorn-Winzeln borders there on the left bank - at km 3.258 of its course it is fed from the right side of the Bannmoosgraben.

At km 8,1 it reaches the center of Seedorf in the community Dunningen at the turning point of a loop to the east, after which it continues south.

At this point, the course of the Eschach is almost twice as long as that of the Neckar, and its catchment area, as well as its water flow, is about three times as large.

bullhead, brook lamprey, thick shelled river mussel, stone crayfish and beaver and are in parts themselves protected as "flowing waters with flooded aquatic vegetation".

Also the high herb fields and strips of floodplain forest along the banks are protected as FFH-habitat type.

In addition, numerous other habitat types can be found on the adjacent meadows and valley slopes.