While tourists are flocking to Achill Island during the current good weather, both visitors and local residents are being advised not to drink from the public water supply - while the reservoirs have now run dry on part of the island.
The Do Not Consume water notice was issued last Friday, and tankers of drinking water are being provided in every village on the island.
The notice not to drink the tap water was put in place following the detection of elevated levels of aluminium and turbidity in the water supply - as the island's treatment plant was unable to cope with demand.
The situation has worsened overnight, as the reservoirs in Slievemore, Dugort East and Dooniver have run dry.
Achill-based Fianna Fail Councillor Paul McNamara says the water shortage affects a large area of the island, and an emergency plan was put in place at midnight.
This involves a number of tankers drawing water to the reservoirs, which should be refilled by evening.
Councillor McNamara says people in the affected areas should have water back in their taps this evening - however, the water is not for human consumption.