Mayor of Galway Niall Ó Brolcháin claims that Galway City Council has "known for five years" about the risk of contamination of public water supplies by the cryptosporidium parasite.
Rapid population growth has meant that water filtration systems in the city and county are not adequate to cope with the organism, and this had been raised at local authority meetings, the Green Party city councillor said yesterday.
The parasite, which is found in water contaminated with sewage and animal waste, can cause diarrhoea and stomach upsets for up to a fortnight. The condition, known as cryptosporidiosis has no cure, and is more serious among immune-compromised groups such as small babies and people with HIV/Aids.
An early peak in reported cases of the illness noted by the Health Service Executive (HSE) West in Galway city and county resulted in the issuing of a "boil water"notice by the local authorities last Thursday. This applies to the city and large parts of the county.
So far, testing has been "clear", according to HSE West, and the alert is due to be reviewed at a meeting today of the local authorities and officials of HSE West's department of public health.
Mr Ó Brolcháin said that filtration systems needed to be upgraded, and local authorities should also take measures to prevent cryptosporidium entering the water system in the first place. The British drinking water inspectorate describes the parasite as a "challenge" to water treatment processes because of its small size and resistance to disinfection. However, the inspectorate said that there is good evidence that careful operation of coagulation/flocculation and filtration can provide consumers with a very high level of protection against exposure. The British government introduced regulations in June 1999 which require water companies to carry out risk assessments in relation to the parasite's potential presence in their works, and where there is a risk companies must ensure that the average number of oocysts is less than one per 10 litres of water.
Commenting on the mayor's concerns yesterday, Galway City Council director of services Ciaran Hayes said it was "not possible" to take measures to prevent the parasite from entering the system and filters "don't catch it". However, specific tests taken over the past week in the city and county were "encouraging", in that the results were clear of the parasite, he said.
A confluence of events at this time of year, involving the lambing season, slurry spreading and heavy rainfall, meant that there was always a risk of it being in the water system, Mr Hayes said.
However, the local authority has applied to the Department of the Environment to double the capacity of water production under the National Development Plan, he said. He added that the local authority thanked people for their co-operation and apologised for the inconvenience.