Traces of potentially harmful E-coli bacteria have been found in St Helena’s water supply. No one is thought to have been infected by the bug.
People on the island have been instructed to boil water for at least a minute before drinking it – even if it looks clean.
The bacteria was found during routine checks, but a government statement said tests had yet to reveal whether it was a dangerous variety. Further tests were being made across the island.
Dr Sarel Bloem, the senior medical officer, says the safety advice applies to the whole island, and not just the areas where water was discoloured by an unrelated problem last week.
Police and the general hospital were issuing sterilisation tablets for people who were unable or unwilling to boil water. Tablets were being distributed to schools, shops and people in sheltered housing.
E-coli is a bacteria that lives naturally in the human gut. Its benefits include producing vitamin K2 and preventing more-harmful bacteria from growing.
But some forms can have serious consequences for vulnerable people, including babies and the elderly. In extreme cases, they can cause death.
Symptoms to watch for include severe abdominal cramps, followed by diarrhoea, nausea, vomiting and fatigue.
However, St Helena Government has stressed that the instruction to boil water is only a precaution, put in place while tests establish whether the E-coli in the island water supply is harmful.
Islanders are encouraged to boil water and then keep it friedges in clean containers.
Boiled or sterilised water must be used for drinking, preparing food and drinks, making ice cubes, washing vegetables or brushing teeth.
It is not necessary to boil water for showering, laundry, or bathing, as long as it is not swallowed. Infants should be bathed with a sponge.
Most water filters will not protect against E-coli.