Trampers used to be able to access Kawahatau Base through private land. This is no longer an option. Access is via the Kawhatau River from the Rangitane road bridge.
If using the Purity Road end access remember to contact the landowner for permission.
http://www.doc.govt.nz/parks-and-recreation/places-to-stay/lodges-cabins-and-cottages-by-region/manawatu-whanganui/kawhatau-base/