The Ochtum begins in Lower Saxony only a few kilometres south of the city of Bremen near Weyhe at the confluence of the Süstedter Bach and the Hache in the lake known as the Kirchweyher See [de].

The river flows through or passes the villages and suburbs of Kattenesch, Huchting and Strom, crosses the Park links der Weser [de] and the Ochtumniederung bei Brokhuchting [de] nature reserve.

A second branch of the Ochtum – its original channel – flows north past Grolland [de] and joins the main river in the nature reserve.

The Ochtum passes Delmenhorst-Hasbergen and Lemwerder-Deichshausen and discharges into the Weser at river kilometre 12.85 between Lemwerder-Altenesch [de; it] and Bremen-Seehausen near Unterweser.

According to the 2000 water quality map by the state of Bremen the Ochtum is classified as Class II, moderately polluted, as far as the district of Bremen-Strom.