Two more water suppliers in Waikato have detected “slightly elevated” levels of arsenic in their water drawn from the Waikato River.
Meanwhile, Auckland’s provider, Watercare, said its water supply had met drinking standards.
Yesterday evening, both Watercare and the Hamilton City Council reported “elevated levels” of arsenic had been detected at two treatment facilities that drew water from the Waikato River.
Watercare said there was “no immediate risk” to public health but reduced production at its Waikato Water Treatment Plant and increased production at its major Ardmore plant.
Today, Watercare reported samples that met drinking standards but the Waipā and Waikato district councils reported “slightly elevated” levels of arsenic to the Water Services Authority—Taumata Arowai.
Levels up in Waipā, but water is still safe to drink
Today’s results in Waipā recorded 0.0138 and 0.0145mg/litre from two treatment plants. The maximum acceptable standard of arsenic for drinking water in New Zealand was 0.01mg/litre.
Despite this, Water Services manager Karl Pavlovich said tap water remained safe for drinking, bathing, cleaning, and cooking, and residents did not need to boil it.
“We have increased the testing of our drinking water to daily to keep a close eye on levels and any changes,” Pavlovich said.
“We have also activated the additional processes we usually use over summer to manage water taste, to help reduce the arsenic levels.”
The council said it had made contact with industry experts to ensure it was doing all it could do.
‘Varying’ test results in Waikato
The Waikato District Council said it had received “varying” test results from its Ngaaruawaahia, Huntly, and Te Kauwhata water treatment plants.
A sample from Te Kauwhata showed a reading of 0.0054 mg/litre, which was well within drinking water standards.
A sample submitted in Huntly read 0.0089 mg/litre, also within drinking water standards.
The Ngaaruwaahia water treatment plant showed a reading of 0.012mg/litre — a “slightly elevated” reading that was consisted with previous tests shared by the Hamilton City Council and Watercare.
Waikato District Council waters manager Keith Martin said the inconsistent readings were likely caused by each plant’s different operations.
Martin said the council planned to inject chlorine at the front end of the treatment process at the Ngaaruawaahia plant tomorrow as part of its operational changes to water treatment plants. This would allow the council to improve water quality based on sample tests if needed.
“We are working very closely with regulators, the Water Services Authority—Taumata Arowa to ensure that we are responding appropriately to ensure the provision of safe drinking water to our community.”
Hamilton’s levels ‘broadly consistent’, council optimising treatment
Hamilton City Council’s sampling showed its water was still safe to drink, with arsenic levels “broadly consistent” with previous elevated readings.
The most recent test result was 0.0123 mg/litre, exceeding the standard by 0.0023mg/litre.
“We’re maximising our current infrastructure’s ability to treat the water and bringing forward commissioning of new infrastructure which treats the water a different way,” unit director Three Waters Maire Porter said.
“We’re also working with an industry expert who has been providing advice to suppliers on this issue and who will be onsite with council’s own specialists tomorrow to provide independent advice.”
She anticipated the combined approach would start to decrease the levels of arsenic in future testing.
“While there’s no issue with the safety of our water supply, we know it’s a concern to our public. We will continue to update our regulator daily and are absolutely focused on meeting all applicable Drinking Water Standards.”
Auckland water within standards
Auckland’s Watercare said a sample taken yesterday showed a result of 0.0081mg/litre — safely within drinking water standards.
“We’re cautiously optimistic but, of course, we will be continuing our daily sampling programme for the time being,” Watercare chief operations officer Mark Bourne
“Water produced at our Waikato Water Treatment Plant passes through a robust multi-barrier treatment process that includes coagulation, clarification, filtration and absorption processes.
“This treatment process is effective in eliminating a wide range of contaminants, including microorganisms, ensuring safe drinking water.”
Production at the Waikato plant was still reduced, meaning more water was being drawn from Watercare’s dams in the Hūnua Ranges.
Watercare encouraged Aucklanders to “take it easy” with their water use because “water is a precious resource”.
“While we are not in a drought, summer is just around the corner,” Bourne said.
