The latest Environmental Protection Agency report on the quality of Irish drinking water shows increased bacterial contamination occurring in public supplies, with 8 per cent failing to reach acceptable standard.
And as much as 36 per cent of group water schemes supplies were deemed unacceptable. Many continue to have water of "appalling microbiological quality" and are "unfit for human consumption", according to the report for 1997, published today.
It notes that frequently in rural areas supplied by group schemes or from small private supplies, "the practice of chlorination, or effective disinfection, may be largely or wholly unknown" despite their vulnerability to contamination by septic tanks or slurry pits.
The safety of such supplies "is dependent on responsible attitudes in rural communities with regard to maintenance of septic tanks and disposal of farm wastes", the EPA points out.
The report, nonetheless, finds the overall quality of Irish drinking water is "satisfactory" and there is "a definite trend towards better quality" in group water schemes. These are mainly supplies in rural areas financed by communities but often with sanitary authority and Department of the Environment assistance.
Absence of coliform bacteria, which mostly arise from human or animal faeces, is used as the yardstick for good quality. During 1997, some 13 per cent of samples had coliform levels in excess of legal limits, up 0.85 per cent on 1996.
Significantly, this deterioration was in public rather than group supplies, though breaches are often minor and due to non-faecal bacteria, indicating a distribution system problem or maintenance is overdue rather than contamination by sewage or farm waste.
Any breaches are, however, unacceptable to the consumer and local authorities must ensure greater compliance, the report says.
On faecal contamination of group schemes, it notes: "There is abundant evidence of the often very severe quality loss in supplies, resulting in waters which are unfit for human consumption." It strongly criticises local authorities for poor monitoring.
"Surveillance of such schemes by the sanitary authorities has been piecemeal and, with some exceptions, unsystematic. However, the sporadic nature of the coverage does not undermine the overall finding that quality problems abound." The extent of the problem and of risk from poor quality water is reflected in the number of schemes in existence: some 5,500 serving more than 150,000 households (possibly as much as 600,000 people), it warns.
The reports also highlights:
a significant rise in aluminium in water. Aluminium compounds are used to treat public water supplies, while excessive levels have been linked to Alzheimer's Disease, though the association is not conclusive.
a welcome reduction in chlorine and fluoride levels in water, but "well over half the exceedances (of these chemicals) are in a concentration band markedly above permitted values".
While the EPA accepts quality problems in group schemes are "being actively addressed" by a partnership between the Department of the Environment, local authorities and the National Federation of Group Water Schemes, it stresses a need for improvement to be "greatly expanded and built upon".
The report evaluates more than 1,000 public water supplies and 1,000 group water schemes, involving more than 100,000 test results, the highest number it has ever evaluated.
Dr P.J. Flanagan of the EPA regional inspectorate said the report underlined the need for vigilance among group schemes and with small supplies where contamination was often caused by run-off from poorly sited septic tanks or slurry pits.
The report includes an overview for the 1995-1997 period. Group schemes in the Co Mayo area were considered "unsatisfactory to a marked degree"; having "a frequent faecal coliform presence which renders such supplies wholly unfit for human consumption".
A "marked rise in coliform exceedances in 1997" was found in Co Wicklow, which reveals a significant and disappointing loss of overall quality. "A marked loss of bacteriological quality" was found in Westmeath's public supplies during 1997.
