The river is of modest flow and is heavily reliant on rainfall with a discharge near its mouth of 1.6 cubic metres per second (57 cu ft/s).

The river is born on the slopes of Madonna dei Monti near Grazzano Badoglio in the Province of Asti, close to one of the springs of the Grana del Monferrato.

Its early course makes an arc through the hills of the Basso Monferrato, heading first west-southwest before curving gradually to west-northwest.

At San Maurizio (near Occimiano), it is joined from the left by a further branch with origins near Terruggia.

Entering the Casalese plain, the Rotaldo River follows a sinuous course, passing through Borgo San Martino, Ticineto, and Valmacca where it is joined from the left by the Gattola.