Senior officials at Clare County Council covered up damning reports of the level of cryptosporidium in the Ennis water supply.
Green party councillor Brian Meaney made the charge after documents secured by The Clare People through the Freedom of Information Act show that the Environmental Protection Agency warned the council in January that the water supply was at risk of another outbreak of cryptosporidium.
Council officials did not make the public aware of the EPA concerns and a month later, an outbreak of cryptosporidium resulted in two children being hospitalised.
The documentation shows that despite a budget of €3 million for a temporary water treatment plant, 25 to 30 per cent of the water going through the plant was not being treated for cryptosporidium.