A new water treatment works is to be transported 128 miles (206km) by road and then taken by ferry before being assembled in North Uist.
Built and tested at Ross-shire Engineering in Muir of Ord, the transportable treatment unit (TTU) is being dismantled into 12 modules.
Over the next three weeks, modules will be taken by lorry to Uig in Skye and from there by ferry to Lochmaddy.
The water works will then be constructed near Lochmaddy.
Scottish Water said the deliveries were being planned in a way to minimise disruption to road and ferry traffic.
Each convoy will have a police escort as it makes its way to Uig via the A832, the A9, the A82 and the A87.
The first two convoys are set to depart from Muir of Ord, near Inverness, at 09:00 on 18 June and on 21 June.
A 150-tonne crane will also be taken over to North Uist for the construction of the water treatment plant.
Scottish Water project manager, Anoushka Ainslie-McAlpine, said the deliveries represented an "exciting milestone" in a £15m project to improve the water supply to customers in North Uist and Berneray.
Corporate affairs manager Gavin Steel added: "We recognise that these deliveries are taking place at a busy time for the Highland transport network and will do all we can to keep any disruption to a minimum."
Construction of the water treatment works is due to be completed by the end of the year.