Residents of Taumarunui and Manunui are being warned to boil drinking water after a filter fault at the nearby Matapuna water treatment plant.
Ruapehu District Council has issued a precautionary `boil drinking water' notice, which will remain in place until at least Monday.
Council acting chief executive Margaret Hawthorne said the notice was purely precautionary and disinfection of the water at the plant was continuing as normal.
Filters had been blocking over the past few weeks, and were taken offline to allow the plant to fill reservoirs before the impending arrival of Cyclone Lusi.
The council is required by the Health Act to issue a precautionary notice.