The Halswell River has a catchment area of 190 square kilometres (73 sq mi), 85% of which fall into Selwyn District with the balance in Christchurch City.

[1] The two main tributaries are Knights Stream (which originates between Prebbleton and the suburb of Oaklands)[2] and Te Tauawa a Maka / Nottingham Stream (which originates in Oaklands).

[3] The Halswell River rises north-west of the Port Hills on the periphery of Christchurch and flows south into Lake Ellesmere / Te Waihora.

[4] Parts of the river originally had the Māori names of Huritini (meaning "many turns"), Te Tau Awa a Maka and Te Heru o Kahukura.

[5] The river was renamed for Edmund Halswell, who was a member of the management committee of the Canterbury Association and arrived in New Zealand in 1841.