A senior health official has indicated that more than 70,000 people in parts of Galway city and south Connemara will have to continue to boil all tap water, or use bottled water, for an indefinite period.
The warning came after 20,000 consumers on the eastern side of the city were told their tap water is now safe to use.
The boil notice for Tuam, Athenry, Headford, Oranmore and Claregalway is being lifted as water supplies are being provided from a County Council-owned water treatment plant on the shores of Lough Corrib.
The contamination of much of Galway's water supply led to an outbreak of the cryptosporidium illness four months ago.
The Director of Public Health in the HSE West, Dr Diarmaid O'Donovan, said work was continuing to try to provide good water to the remaining districts affected.
