He said the appliances on board were run by a diesel-powered generator and, ideally, they would plug into power and water sources wherever possible too.
Knight said New Zealand's rate of homelessness was particularly alarming and they hoped to have the same "massive" impact that they've had across the ditch.
About 800 people were sleeping rough in Auckland last month, along with another 2874 people, including 1299 children in temporary and emergency accommodation, according to initial figures released from the Ira Mata, Iri Tangata: Auckland's Homeless Council.
Knight said it's expected that like any new service, it'll take time for people to warm to it and take advantage of it.
He said it was just a matter of time before more of the vans were brought in and rolled out around New Zealand.
The service is partly funded by the Ministry of Housing and Urban Development.
The Minister for Housing and Urban Development Phil Twyford said while support services are working hard to reduce homelessness and get roofs over people's heads, the laundry service goes some way to bringing rough sleepers one of the simple things many take for granted.