Galway Corporation intends to continue testing water supplies over the weekend following detection of contaminants in the centre city area.
A public health warning has been issued as a "precautionary measure", according to the local authority. It advises the public to drink commercial bottled water or boiled water only. The corporation is confident that the "slight" contamination can be cleared over the next two days.
The local authority is understood to have issued the warning yesterday under pressure from the Western Health Board, following identification of coliform bacteria in two areas in the city centre.
The pollution appeared to be confined to the High Street/ Quay Street area, but a warning notice was issued extending across to Ballybane and Dough iska. The west side of the city is understood to be largely unaffected.
Mr Tom Kilgarriff, director of services and city engineer with Galway Corporation, said the cause might be traced to work on renewing the water mains. Sediment may have gathered in temporary "dead ends" where new pipes were patched on to old, and this may have attracted the coliform bacteria. Remedial measures were being taken, he said, including flushing mains, installing hydrants to speed this up and increasing the rate of disinfectant use.
Mr Kilgarriff said there was no risk to human health. This was reiterated yesterday by Dr Declan McKeown, acting director of public health with the health board. Dr McKeown told The Irish Times that no faecal coliforms such as E.coli had been identified, and so there did not appear to be any immediate health hazard. Coliform bacteria are known as indicator bacteria, but tests had shown no evidence of further more serious contamination, he said.
A letter sent to all restaurants, pubs and hotels in the city outlines a series of precautionary steps which should be taken. It says water should not be used for food preparation or drinking and ice must not be made. Automatic ice-making machines should be disconnected from the power supply, it advises.
Equipment, worktops, chopping boards or other surfaces which come into direct or indirect contact with food must be cleaned and sanitised, using water that has either been boiled before use or which has been suitably disinfected using a food grade disinfectant.
Crockery, cutlery and other equipment should be washed in automatic machines which achieve a rinse temperature of over 82 degrees Celsius, it advises. Otherwise, a double bowled sink where water in the rinse sink is at least 82should be used.