Excessive levels of nickel in the water in the New Caledonian village of Kuto have prompted the authorities to urge people to stop drinking tap water.
The public broadcaster said the nickel content was 30 times the level to be considered safe by the World Health Organisation.
Kuto, which is a prime tourist destination on the Isle of Pines, has been identified as the only place with such issues.
The immediate cause had not been identified but the broadcaster said repeated fires had destroyed the vegetation and eroded the soil.
Local authorities will reportedly provide tanks with drinking water for residents and tourists.
The public has been told that using the water for other purposes poses no risk.