Algal build-up in the Roundwood reservoir has been blamed for a disruption to water services in parts of Wicklow and south Co Dublin.
Taps have been "running dry" during the daytime in several parts of the Dún Laoghaire-Rathdown area for the past two weeks, Labour's TD for the area Eamon Gilmore said today.
The water supply to the area is managed jointly by Dún Laoghaire-Rathdown County Council and Dublin City Council.
A Dublin City Council spokeswoman said the problem was localised in the reservoir at Roundwood, Co Wicklow, which provides water for the affected areas. She said algal build-up was a natural phenomenon that was not unusual at this time of year.
Mr Gilmore claimed that two weeks after the problem was revealed, there is no indication of a when a solution will be found.
"It is simply incredible that in this day and age, council officials and engineers are incapable of solving this particular problem," Mr Gilmore said.
"What's more worrying is that they don't even seem able to fully identify the cause, and certainly don't appreciate the distress that it is causing for young families, elderly people and other householders."