Unsafe water entered the public drinking water supply at two water treatment plants last month, the Environmental Protection Agency has confirmed.
The failures occurred at the Ballymore Eustace water treatment plant and at the Creagh water treatment plant serving Gorey in Co Wexford.
There has been 52 confirmed cases of illness associated with the Gorey outbreak, including bacteria linked to E. coli, with a number of associated hospitalisations.
EPA Director General Laura Burke said there were unacceptable delays in notifying her organisation and the Health Service Executive about the incidents.
This meant that 900,000 water consumers were left unaware of the failures and did not have the opportunity to protect themselves.
Investigations at both plants revealed what the EPA described as "abject failure" of managerial oversight, operational control and responsiveness by Irish Water and local authorities in terms of their respective roles to deliver safe and secure drinking water.
Ms Burke said immediate actions must be taken by Irish Water and the local authorities to ensure these failures do not arise again.
The EPA investigation at Ballymore Eustace revealed that the plant produced unsafe drinking water for a period of up to 10 hours on 20 to 21 August, due to the loss of the Cryptosporidium treatment barrier compounded by inadequate disinfection.
This is the largest water treatment plant in the country, serving approximately 877,000 consumers in the greater Dublin area.
The incident was not notified by Irish Water to the EPA or to the HSE until 1 September.
This prevented a timely risk assessment of the impact on drinking water quality and to allow interventions to be taken that could have protected public health.
The EPA investigation at the Gorey water treatment plant in Co Wexford found that a power failure and a chlorine pump failure resulted in water leaving the plant and entering the public supply without the appropriate level of disinfection.
This went on for approximately five days between 19 and 24 August.
Neither the EPA nor the HSE were notified until 26 August, preventing a timely risk assessment of the impact on drinking water quality and to allow interventions to be taken that could have protected public health.
In the case of Gorey's water supply, serious illness was detected in the community.
The EPA also said that the main issues highlighted by these incidents include:
- The abject failure of managerial oversight, operational control and responsiveness by Irish Water and local authorities in terms of their respective roles to deliver safe and secure drinking water.
- While Irish Water has the primary responsibility for the safety of the water supply, the failure to report incidents between the local authorities and Irish Water prevented a timely risk assessment of the incidents and resulted in unacceptable delays in notifying the EPA and HSE.
- These unacceptable delays in reporting and in particular the failure to consult with the HSE as to the risk to public health during the incidents, meant that there was no opportunity to issue boil water notices to approximatelt 900,000 consumers of both supplies, which would have served to protect public health until issues at the plants were resolved satisfactorily.
- Additional unreported incidents were uncovered by EPA inspectors during the auditing process which supports the EPA's view of abject failures in managerial oversight, operational control and responsiveness to recognise the seriousness of these incidents for public health.
The EPA said that while it is satisfied that both plants have now returned to normal operation since the incidents, "immediate and significant improvement" in the provision of water services by Irish Water and local authorities is required to ensure the public are provided with safe and secure drinking water and that public health is protected.
The General Manager of Irish Water, Eamon Gallen, said that in both incidents Irish Water and the local authorities who operate the water treatment plants on its behalf fell short of the standards required to protect public health.
He said Irish Water had not been notified in a timely manner that issues relating to the disinfection process at both plants had arisen and that this had potentially put public health at risk.
Irish Water said it agrees that issues related to notifiable incidents identified by the EPA require urgent action.
The Minister for Local Government, Darragh O'Brien, who was informed of the matter by the EPA in a letter earlier this week, said the failures were concerning and unacceptable.
He noted, however, that both incidents have since been rectified and the water from the two plants is now safe to drink.
Mr O'Brien said he would meet the Managing Director of Irish Water and both the Chief Executives of Dublin City Council and Wexford County Council tomorrow morning "to consider what further steps are required to ensure our water supplies are safeguarded".