E.coli has been discovered in a village water supply in Lewis.
Residents have been told to boil water before drinking it or cooking with it.
Scottish Water which is investigating the cause said some 218 properties in the Tolsta district are affected.
Bottled water will be provided to affected households until the water supply is safe.
A Scottish Water spokesman said e.coli was found following a routine sample taken from the Tolsta reservoir.
He added: “We are working closely with NHS Western Isles.
“Bottled water will also be provided to affected customers as a further measure until they receive a letter to say the notice has been lifted.
“We are continuing to focus on returning supplies to normal and would like to thank customers for their understanding and patience.”
Samples of the water supply are being sent to a mainland laboratory for testing.
Water personnel and contractors were yesterday working at the water tank which sits on top of a hill above the scenic village.
More Scottish Water staff were busy at the North Tolsta treatment works at the entrance to the district.
The bacteria is in a holding tank on the supply pipeline to Tolsta.
Other villages supplied by Loch Ionadagro main reservoir are not affected.
Tolsta resident Annabel Smith said there was “a bit of panic” locally when it emerged that e.coli was responsible for the safety warning.
Councillor John A. Maciver said the village supply tank was 50 years old and should be upgraded.