A water quality test conducted by the National Disaster Management Office showed that water in the Reef Islands of Temotu Province is not fit for use.
The water supplies have been contaminated by ash from the Tinakula volcano.
The volcano erupted in the early morning of October 21 and sent black ash into nearby communities.
The National Disaster Management Office urged area residents to protect water tanks after the eruption began, but the ash still affected some water supplies.
Provincial Disaster Officer for Temotu Province George Tego said as communities work to clean up their water sources, they will rely on more than 11,000 cartons of water that were recently distributed to the islands.