Call for cuts to band-aid solutions over contaminated water

20 October 2016

A small number of water suppliers are dealing with contaminated water problems through band-aid solutions, according to the authors of a study on failing the drinking water standards.

The report, Failing the Drinking-Water Standards – Insights from the Annual Survey, was presented to the Water New Zealand Annual Conference in Rotorua today.

ESR Science leader Dr Chris Nokes says that while the vast majority of New Zealand communities have access to good quality water, a review of annual survey data reveals that more than ten percent of the zones, or water supply sub-areas, serving more than 500 people in 2013-14, failed to meet the Drinking Water Standards because E. coli was detected on too many occasions, or there was inadequate monitoring. A little more than a quarter of these zones had failed in at least three of the four previous years because of the detection of E. coli.

Dr Nokes stresses that these results don’t necessarily mean that the drinking water was unsafe. But he says the presence of E. coli does indicate faecal contamination of the water and this means further investigation is needed.

He says it’s important to find out the cause of the contamination, especially when there are repeated cases of failure. Intermittent, low levels of E. colicontamination can be difficult to investigate.

“In circumstances where there have been a high number of transgressions, or failure to meet the standards, the cause could be an ongoing problem needing attention, such as inadequate treatment or contaminants entering the water after treatment.

Temporary chlorination is often used to provide a short term solution but does not address any underlying issues.

Dr Nokes believes that, to reduce levels of failure, all water suppliers should be encouraged to permanently treat water with chlorine and that, where necessary, filters be installed in treatment plants before the water is disinfected.

“We also need to ensure that suppliers’ water safety plans include a requirement that causes of contamination are investigated and then steps are taken to address those causes.

Water New Zealand Chief Executive John Pfahlert says he hopes the investigation into the Havelock North contamination will provide a real opportunity to investigate the significant challenges that many local authorities face in ensuring communities have safe drinking water and that any contamination outbreaks are investigated and dealt with appropriately.

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