Laudach is a river in the Austrian state of Upper Austria. With the outer Laudach, the river reaches a length of something over 20 km. The Laudach is a left and the main tributary of the Alm.
The longer, „äußere“ (outer) Laudach is the output of the Laudachsee in Gmunden. It passes from the south direction the city areas of Sankt Konrad, Gschwandt, Kirchham and Vorchdorf.
The smaller tributary, the „innere“ or „dürre“ (inner) Laudach, has its source in the municipality of Kirchham. It forms from two sources, the „Platzbach“ and the „Edlbach“. The water stems from hills, which lay like a horse shoe around the village Hagenmühle in Kirchham. These three hills are the Wiesberg, Hacklberg and Feichtenberg. Also from southern direction coming, this right tributary discharges into the "äußere" Laudach north of the center of Vorchdorf.