The Clutha and Waitaki District Councils' water supplies had E.coli transgressions and neglected to adequately protect consumers at times when the drinking water was known to be contaminated, the Ministry of Health's annual review of drinking water quality shows.
The report, which follows the review of drinking water supplies between July 2007 and June 2008 by the Institute of Environmental Science and Research, advised the councils to urgently review and improve their "corrective action procedures" following the bacteriological transgressions.
One of the reasons for monitoring water supplies is to identify hazards and remedy them rapidly.
The number of people served by supplies in which E.coli transgressions occurred, and were not appropriately followed up by immediate corrective action, increased markedly between 2006-07 and 2007-08.
"This is of concern because failure to remedy the cause of a transgression subjects the population to prolonged exposure to faecally-contaminated drinking water and imposes an unacceptable risk of waterborne disease on the community," the report said.
The Clutha and Waitaki District Councils were among 38 local authorities nationwide singled out in the report for neglect.
The Waitaki District Council was one of eight reported for the same practice in the previous review.
"The Clutha and Waitaki District Councils need to take appropriate corrective action following all E.coli transgressions.
"It is suggested that the councils be reminded of the public health significance of faecally-contaminated drinking water and, as this was also noted in the previous report, the Drinking Water Assessors (DWA) are requested to investigate and report progress to the Ministry of Health," the report said.
Waitaki District Council chief executive Michael Ross was keen to respond last night to the claims, but wanted to speak to his water staff first.
However, he said the council operated more rural water schemes than most local authorities, and they were prone to contamination.
"We are running water schemes with a lot more potential for E.coli contamination. Stock contamination of water supplies has a big effect."
Mr Ross denied consumers were not well informed of bacteriological transgressions.
"Some of our users are on permanent boil-water notices. What more can we do?"
Clutha District Council chief executive Charles Hakkaart also disagreed with the assessment.
"We are very conscientious about our testing and reporting," he said.
He declined to comment further until he and his staff had had a chance to read the report.
Across the Otago and Southland region, the report found bacteriological compliance had improved overall during the past year - particularly at schools and early childhood centres.
This was mainly due to the concerted efforts in Southland.
However, many schools still reported E.coli in their water supplies during 2007-08.
Concerns were raised in the report about the lack of protozoal compliance in the majority of drinking water supplies in the Otago and Southland region.
Protozoal compliance was achieved in only five local authority-run plants serving 11 zones in the Otago and Southland health district.
The report recommended the optimal means of achieving protozoal compliance should be determined and implemented for the remaining supplies.
Monitoring of priority 2 (P2) chemical determinands was also found to be poor in several districts.
Where suppliers are reluctant to monitor for hazardous metals in drinking water, the need to monitor for these determinands can be eliminated (provided the necessary public warnings to flush taps before drawing water for consumption are given), if the suppliers carry out the monitoring required to show that the metals arise from plumbosolvency - the ability of water to dissolve lead.
The Invercargill City Council was commended in the report for maintaining complete bacteriological, protozoal and chemical compliance in its supplies during 2007-08, and for its development of a draft public health risk management plan for both of its supplies.
Water nasties
- E.coli: Bacteria commonly found in the lower intestine of warm-blooded organisms. Most E.coli strains are harmless, but some can cause serious food poisoning in humans.
- Protozoa: Protozoa are one-celled animals such as cryptosporidium and giardia. Priority two (P2) chemical determinands: Chemical contaminants in drinking water which may be of potential health concern.
