PROCTER & Gamble said that a foul drain within the industrial estate which was not its responsibility - was behind the incident.
The company added that it understood the frustration caused by the interruption of the water supply.
Ms Sally Woodage, public affairs manager of the company, said it was clear from the EPA report that further investigation would be necessary to establish how the contamination had occurred. Procter & Gamble, she added, valued its role in the Nenagh community and would continue to assist the EPA in its deliberations.
Process effluent from the plant was discharged into the foul drain with the permission of the local authority, a statement from the company explained. The EPA report had referred to a "small leakage" within the P&G site, but this had been dealt with quickly
"Nevertheless, the company is concerned that any leakage has occurred and has taken steps to ensure it will not happen again.
SFADCo said that independent tests by consultants had confirmed that no effluent was leaking from its pipes. It added that if further tests revealed any leaks action would be taken.
A spokesman for Tubex said late last night that the company was surprised at the contents of the EPA report which it received yesterday. It had contacted experts in the relevant field yesterday and would be contacting the EPA as soon as possible on Monday to obtain their assistance.
The Mid Western Health Board said that expert toxicology advice suggested that at very small parts per billion, chemical residues were so low as not to cause concern for public health. No communicable diseases had been notified for the Nenagh urban area since the beginning of August, a statement added.
Nenagh Urban District Council said the question of prosecuting SFADCo and Tubex was being examined both by the UDC and Tipperary (North Riding) County Council. An alternative borehole had been drilled, the UDC added, and further tests would be carried out by the health board before the supply was declared fit for human consumption.
Despite a request to do so, the UDC did not deal in its statement with the EPA suggestion that its own sewer may have been a contributory factor to the pollution.
The Minister for the Environment, Mr Howlin, said the report demonstrated the value of an independent role for the EPA. Its recommendations would reinforce the Department's existing guidelines for the protection of drinking water.
All necessary action, he added, would be taken to ensure that local authorities implemented the precautionary recommendations involved, particularly those concerning risk assessment of all groundwater sources of public drinking water.
He said that while the new borehole would bring uncontaminated water supplies on stream within a week, this would be no more than a temporary solution. His Department had sanctioned a regional water scheme for Nenagh, costing £11.5 million.
Work has already started on the scheme, which will make all other sources of domestic supply in the town redundant.
Greenpeace said that the EPA report had left questions unanswered. "In particular, the report calls into question the effectiveness of a system which has allowed industrial operations to continue unlicensed, and therefore presumably unmonitored, while posing such a serious threat to public health and the environment.
Greenpeace requests the EPA to state on what legal grounds operations are to be allowed to continue until a decision is made whether or not to issue a licence," it said in a statement.
"Three major questions remain for the EPA today. How many other unprocessed applications for licences for activities already in operation is the EPA presently considering, and what monitoring of these activities is being done in the meantime?" Greenpeace asked. "Will the EPA use the full powers of its own Act against polluters?"
The organisation has written to the Mid Western Health Board and the Ministers for Health and the Environment on the public health implications of the incident.