Officials in Galway are continuing to try to find ways of limiting the spread of a serious outbreak of gastro-intestinal illness.
Their attempts come as water pollution problems worsen in Galway city and a large part of the county.
90,000 people are affected as water mains have been contaminated by the cryptosporidium parasite carried into Lough Corrib from adjoining farmland.
Council engineers are today trying to find ways of minimising parasite levels, particularly in the Headford area where there is serious contamination.
The Mayor of Galway, Niall Ó Brolcháin, told RTÉ News there were serious concerns about the impact the water contamination was having on the city's tourist industry, and a long-term solution will require major investment in better treatment systems.
Ciarán Hayes, Director of Services with Galway City Council, told RTÉ Radio's Morning Ireland that the situation looks like going on for a number of weeks.
He emphasised that boiling water is sufficient at an individual or household level to deal with the parasite.
Mr Hayes revealed there are two water works in Galway city. One fully treats the water and gets rid of the parasite; the other is around 50 years old, which produces 30% of the water supply, does not. The water from both goes into the same reservoir.
Outbreak 'very serious'
Dr Diarmuid O'Donovan, from the Health Service Executive Western Region, described it as a very serious outbreak.
He said there had been 64 laboratory-confirmed cases since the start of the year, 40 since the beginning of March.
Less than six people have been hospitalised, but of those, some had been seriously ill. He said for most healthy people, the bug will cause a diarrhoeal illness for two weeks, longer than normal stomach bugs.
But for those with a weakened immune system, such as cancer patients and transplant recipients, it can be very serious, long lasting and can occasionally be fatal, Dr O'Donovan said.
He added that particular contacts are being made with those involved in food preparation and those in hospitals, nursing homes and crèches.
