At first it flows generally south from its origins in the Tararua Range west of Ōtaki.

It turns south-east once it reaches the plain where it passes to the north of Greytown and flows into the Ruamahanga River at Pāpāwai.

Its main tributary is the Mangatarere Stream.

[1] Some of its water reaches Lake Wairarapa directly through many channels and irrigation features in Greytown's fruit-growing district.

This article about a river in the Wellington Region is a stub.