Tributaries of the Pienaars River include the Moreletaspruit (alternative spellings: Morelettaspruit, Moreleta Spruit).

[1] Note that the above-mentioned Moretele river section is 60 km away from the Moreletaspruit and these two should not be confused with one another.

It originates east of Pretoria, City of Tshwane, Gauteng Province, flowing northwards into Roodeplaat Dam (north of Mamelodi), which is also fed by the Hartbeesspruit and its tributary, the Moreletaspruit.

The semi-stagnant water here and below the dam wall harbours quantities of cyanobacteria and its algal blooms.

The river continues its northward course through the Dinokeng Game Reserve, where it is joined by the Boekenhoutspruit from the east, before passing under the N1 and turning westward towards Pienaarsrivier, the eponymous hamlet on its right bank, and Zaagkuilsdrift.