The Pienaars River originates east of Pretoria, City of Tshwane, Gauteng Province, South Africa, flowing northwards into Roodeplaat Dam (north of Mamelodi), from where it carries on northward until it passes under the N1 and turns westward. North of Makapanstad the Apies River (or rather a short section of the Tshwane River) joins it. The Pienaars continues flowing westward to the Klipvoor Dam. About 25 km further downstream it joins the Crocodile River.