There are now 93 reported cases of serious gastric illness linked to contaminated water in Galway city and county - but it is thought the actual number may run to hundreds.
More than 90,000 people are still affected by the presence of the parasite cryptosporidium in the water supply in Galway city, Barna, Moycullen, Tuam, Headford, Athenry and Oranmore.
Before the weekend, 79 cases of cryptosporidiosis had been reported. The incident response team set up by Galway city and county councils and the HSE West yesterday confirmed that this number had risen to 93.
Cryptosporidiosis is a diarrhoeal disease caused by microscopic waterborne parasites.
The crisis over Galway's water supply dominated yesterday's monthly meeting of Galway County Council, when members highlighted the disruption the problem was causing in homes, schools, farms and in work places.
Cllr Fidelma Healy-Eames (FG) said that although the number of cases was put at 93, several hundred people may be suffering from mild symptoms of the illness.
The meeting was told by several councillors that the catering and tourism sectors were being badly hit.
The instruction to boil water before use, which was first issued on March 15th, is being repeated daily and it now appears that this could continue into the summer.
The HSE West, along with Galway city and county councils, yesterday reiterated that it was essential for people to boil all water intended for drinks, food preparation and cooking.
Tap water should not be used even for brushing teeth or for making ice, the health and local authorities have warned.
Householders have been told that domestic water filters will not make water safe to drink.
However, bottled water from natural springs has so far been given the all-clear.
Environmental health officers have again stepped up their monitoring of water supplies and yesterday met with swimming pool and leisure centre operators in Galway city and surrounding towns to brief them on the situation.
The response team is being advised by the Environmental Protection Agency and the Health Protection Surveillance Centre.
Jim Cullen, director of water and environmental services with the county council, said every effort was being made to have a normal water supply restored as soon as possible.
He said the "boil water" notice would continue until all water tests were clear on a consistent basis. He did not rule out the lifting of the restriction in some areas, but this was unlikely to happen soon.
"It is extremely difficult to put a timeframe on this. It could go on for some time," he said.
He said the cause of the contamination was not known, and thought the "undue emphasis" placed on the agriculture sector had been unfair.
Several councillors called for free bottled water to be made available, with Cllr Healy-Eames saying it was vital for people to have unlimited drinking water available to them.