It is rising at the Northern side of the town Rosbach vor der Höhe located at the edge of the Taunus mountain range.

Nowadays, the actual location of the spring cannot be determined due to the growing development of the village Ober-Rosbach, part of Rosbach vor der Höhe.

On raining days the water is cloudy, as the source of the Fahrenbach is located at a former quartzite quarry.

On reaching Nieder-Rosbach the river Rosbach feeds the Wasserburg followed by several small ponds inhabited by duck populations which contribute to the poor water quality.

From now on, the river is called Gänsbach, passes a small forest, and flows to Nieder-Wöllstadt.