Scottish Water is to spend £44m upgrading treatment works on the Western Isles - the biggest project of a £2.4bn investment programme.
Scottish Water said drinking water quality will be improved
The utility company said drinking water supplies will be improved across the islands including Stornoway, Barra, North Lochs, Benbecula, Tarbert, Berneray, Geocrab and Lemreway.
Investment will also take place at Cliasmol, Rhenigadale and Ardvourlie.
Most projects will begin before the end of the year, said Scottish Water.
Calum Mackenzie, Scottish Water's team manager for the Western Isles, said it marks another phase in massive investment in the area.
He said: "Since we launched in 2002, we've invested over £26million in the Western Isles - that's over £2,000 per household compared to a Scottish average of £800."