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Testing has revealed elevated arsenic levels in drinking water from Waipā and Waikato District Councils.
Watercare’s Auckland samples show arsenic levels well below the maximum acceptable value.
Authorities are monitoring the situation and adjusting treatment processes to ensure safe drinking water.
Auckland’s Watercare says it is meeting drinking water standards - but testing has revealed two more water suppliers in the Waikato District have elevated arsenic levels in drinking water.
Water Services Authority head of operations Steve Taylor said Waipā District Council and Waikato District Council tests have revealed slightly elevated levels of the toxic heavy metal, joining Hamilton City Council readings from earlier this week. All three drinking water suppliers draw from the Waikato River.
“We are confident that the drinking water suppliers are responding appropriately to reduce the level of arsenic in the supply by adjusting their treatment processes,” Taylor said.
“We are monitoring the situation closely and will continue to work with the drinking water suppliers to ensure they are taking appropriate steps to manage and resolve the issue.”
National Public Health Service regional clinical director Dr William Rainger said people who drink treated water sourced from the Waikato River should not be alarmed.
“Drinking water with slightly elevated levels for a short period of time is unlikely to impact people’s health. You do not need to boil your drinking water. It is safe to drink,” he said.
Auckland drinking water ‘comfortably below’ maximum acceptable value
Watercare has recorded samples that meet drinking water standards in Auckland.
“This afternoon, we were pleased to report a result to the Water Services Authority - Taumata Arowai of 0.0081 milligrams per litre in a sample taken yesterday. This is comfortably below the ‘maximum acceptable value’ for arsenic of 0.01 milligrams per litre,” said Watercare CEO Mark Bourne.
“We’re cautiously optimistic, but of course will be continuing our daily sampling programme for the time being.
“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 micro-organisms, ensuring safe drinking water.”
The Watercare response included reducing production at its Waikato treatment plant and increasing production at its Ardmore plant.
“This means we are drawing more water from our dams in the Hūnua Ranges. While we are not in a drought, summer is just around the corner – so we encourage Aucklanders to take it easy with their water use because water is a precious resource.”
New Zealand Food Safety deputy director general Vincent Arbuckle said arsenic levels detected in the Waikato River are not harmful to animals and there was no evidence water used for animals or food production was unsafe.
“If there was a risk to food safety we would take appropriate action to protect consumers, including recalls,” Arbuckle said.
Waikato’s mixed results in testing
The Waipā District Council said it tested its treatment plants yesterday after elevated levels of arsenic were detected by Watercare and Hamilton City Council in their treated water sourced from the river.
“The results received today recorded 0.0138 and 0.0145 milligrams per litre from two Waipā water treatment plants. The maximum acceptable standard for arsenic in New Zealand drinking water is 0.01 milligrams per litre,” it said.
It said tap water remained safe for drinking, bathing, cleaning, and cooking.
The Waikato District Council had mixed results in its testing, with its Huntly and Te Kauwhata water treatment plants showing a reading well within drinking water standards for arsenic levels, but an elevated reading of 0.012 at its Ngāruawāhia plant.
Elevated readings of arsenic have been recorded in the Waikato River. Photo / Doug Sherring
Waikato District Council waters manager Keith Martin said this was likely because the treatment plants operate differently.
“As of tomorrow, we will start injecting chlorine at the front end of the treatment process at the Ngāruawāhia plant as part of our operational changes to our water treatment plants to improve water quality if, or when needed, as a result of sample tests,” he said.
“We are working very closely with regulators, the Water Services Authority - Taumata Arowai to ensure that we are responding appropriately to ensure the provision of safe drinking water to our community.”
Watercare Waikato said it was taking daily samples for testing from all plants that draw water from the Waikato River.
The Waikato Regional Council is still awaiting test results from samples collected from the Waikato River on Wednesday - where samples were taken from Lake Ōhakuri, Lake Arapuni, Karāpiro, Narrows Landing, Horotiu and Rangiriri.
The Hamilton City Council said it was taking two approaches to dealing with the form of arsenic currently being found in the river.
“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. 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,” said Three Waters unit director Maire Porter.
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