Higher than usual levels of manganese and iron have resulted in brown-tinted drinking water for Hauraki Plains residents this week. A combination of recent high rainfall and network issues that have stirred up the sediment layer in our pipes have caused the spike in manganese and iron.
No health and safety risk
The discoloured water looks unappealing and can cause problems on white-sheet-washing day, but health and safety is not an issue. According to the World Health Organisation people you would need to drink 2 litres of water containing high levels of manganese every day for 70 years before it became harmful to your health. Most of the time we're able to treat the water and keep it at a level where it doesn't cause staining of whites (below 0.04mg). This is also well below the maximum acceptable value of 0.4 mg per litre (according to NZ Drinking Water Standards).
Having said that, the health and safety of our communities is our number one priority so we’ve been in touch with the Ministry of Health and the Medical Officer of Health who are happy with the way we are managing the current spike in Manganese and have raised no health and safety concerns.
While there are still problems in pockets of the Plains, most people have reported an improvement and this should continue over the next few days. If you continue to have issues, please don't hesitate to let us know.
Long term solutions on the radar
Hauraki Plains drinking water is sourced from the Waihou River and treated at the Kerepehi Water Treatment Plant.
Testing over the past few years has shown this river has high levels of manganese and iron. Usually we can reduce it to an acceptable level, but the levels fluctuate constantly which means that we don’t always get it spot on.
We’re investigating possible long term solutions to make sure that we get it spot on all the time. We'll Keep you updated on our progress with this.
Thanks for your patience and understanding
We thank you for your ongoing patience and understanding while we work to resolve the current issue and look further into a solution for the longer term.