Irish Water and the Health Service Executive insist that there is no contamination of Portlaoise's water supply.
The HSE said there is no evidence of an outbreak of cryptosporidiosis in the Portlaoise area. It said it investigates all cases of cryptosporidium infection of which they are notified.
Irish Water said any decision to issue a drinking water restriction is taken on the advice of the HSE who are the body responsible for public health.
Irish Water said water quality sampling has confirmed that the Kilminchy public water supply meets the requirements of the European Union (Drinking Water) Regulations and is safe to drink.
A member of the public contacted the Leinster Express this week saying she and other people had been confirmed as having the crypto bug.
The Enviornmental Protection Agency confirmed that Portlaoise's water supply has been on the Remedial Action List since September 2014.
The EPA says there is no UV shield in place to protect against the crypto bacteria entering the drinking supply.
Irish Water has appointed a expert to report on what is needed. It recently said it was upgrading the plant in other ways.
The company said the water being supplied from the Portlaoise public supply is consistently monitored by Irish Water to ensure it continues to meet all the Drinking Water Regulations quality standards. “From the results received to date of sampling undertaken on the Portlaoise Public Water Supply Irish Water can confirm that there have been no detections of Cryptosporidium,” said a statement.
Irish Water said it has a compliance monitoring programme in place for every public water supply in the country to ensure that drinking water is adequately monitored and complies with legislation.
When any drinking water exceedance occurs, Irish Water notifies the Health Service Executive (HSE) and requests advice relating to matters of public health.
When an exceedance occurs for microbiological or chemical parameters Irish Water will also notify the Environmental Protection Agency (EPA). All parameter exceedances are fully investigated to determine the cause and to ensure that appropriate corrective actions are carried out. Results of investigations and corrective actions are shared and reviewed with both the EPA and HSE.
“There is a robust and collaborative relationship between all stakeholders. Where the HSE deem an exceedance to be a risk to public health, the customers within the supply area are notified as required,” said Irish Water.