Six more people have been confirmed to be infected with the parasite cryptosporidium in the past 24 hours in Queenstown Lakes District.
In a statement, Southern Medical Officer of Health Emma Sherwood said the source of infection had yet to be identified and investigations were ongoing.
A boil water notice remains in place for properties serviced by a council water supply in Queenstown Town Centre (out to Industrial Place), Queenstown Hill, Frankton Road and suburbs on the hill above Frankton Road, Fernhill and Sunshine Bay, Frankton, including Five Mile, Remarkables Park and Glenda Drive, Quail Rise, Kelvin Heights, and Hanleys Farm.
National water regulator Taumata Arowai has served a compliance order on Queenstown Lakes District Council for its Two Mile water treatment plant, which does not have a protozoa barrier to stop cryptosporidium entering the water supply.
The boil water notice must stay in place until it is upgraded or switched to another supply.
The area's other treatment plant, Kelvin Heights, had a protozoa barrier but there were doubts it was working, the regulator said.
Queenstown Lakes District Council Mayor Glyn Lewers has said the council was opting for UV treatment for the Two Mile treatment plant as it was the quickest to install.
The town has also been hit by heavy rain causing flooding and damage to property earlier this week. The state of emergency declared on Friday will continue for seven days.
Authorities were warning people to avoid contact with flood waters, which they said people should assume were contaminated with sewage.
RNZ
