Ten people were evacuated from two homes in Coal Creek, near Greymouth, due to flooding on Wednesday.
Heavy rain and winds battered the district.
One of the affected residents, Marie McCrudden, told Radio New Zealand's Checkpoint programme on Wednesday her household woke up to find water levels rising quickly.
Ms McCrudden says water was bubbling up through the pipes in the bathroom and was waist deep in places outside the house.
The residents have been temporarily relocated.
The Grey District council said Range Creek burst its banks affecting lower Cobden, but it is localised and not threatening any housing.
There was also limited flooding in Preston Road and Coakley Street in Blaketown, and limited flooding in Shakespeare Street and Alexander Street.
The council said the Grey River was not at risk of flooding on Wednesday.
Parts of State Highway 6 from Runanga to Greymouth and Inangahua to Inangahua Junction have reopened on Wednesday night.