Two more water suppliers in the Waikato Region detect slightly elevated arsenic in their water, while Auckland’s Watercare says it is meeting drinking water standards

Joint media release

Today, Waipā and Waikato district councils joined Hamilton City Council in reporting slightly elevated levels of arsenic in recent samples of treated water to Water Services Authority - Taumata Arowai. In Auckland, Watercare reported samples that meet drinking water standards.

Head of operations for Water Services Authority - Taumata Arowai, Steve Taylor, says the drinking water suppliers all 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.

“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 says that people who drink treated water sourced from the Waikato River do not need to be alarmed. The limits in the New Zealand Drinking Water Standards are based on the level of risk from a lifetime of drinking the water.

“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.”

New Zealand Food Safety’s deputy director general Vincent Arbuckle says, “The levels detected are not harmful to animals and there is no evidence water used for animals or food production is unsafe. If there was a risk to food safety we would take appropriate action to protect consumers, including recalls.”

Auckland’s water supply meets drinking water standards

Watercare chief operations officer Mark Bourne says the company’s latest test result fully complies with drinking water standards for New Zealand.

“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.

“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 microorganisms, ensuring safe drinking water.”

Bourne says the company’s operational response includes reducing production at its Waikato treatment plant and increasing production at its Ardmore plant.

“As a prudent water supplier, we’ve made the decision to reduce production at our Waikato Water Treatment Plant while we work with Waikato Regional Council to understand what has caused the changes in river water quality.

“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.”

Waipā water safe to drink, increase of arsenic levels found

Waipā water remains safe to drink following slightly elevated levels of arsenic found in the district’s treated drinking water.

Waipā District Council tested their treatment plants yesterday after Watercare and Hamilton City Council discovered a small increase in levels of arsenic in their treated water taken from the Waikato 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 0.01milligrams per litre.

Water Services Manager Karl Pavlovich said the tap water remains safe for drinking, bathing, cleaning, and cooking, and there is no need for residents to boil their water.

“We have increased the testing of our drinking water to daily to keep a close eye on levels and any changes,” said Pavlovich. “We have also activated the additional processes we usually use over summer to manage water taste, to help reduce the arsenic levels.”

Contact had been made with industry experts to ensure the council was doing all it could to manage the situation.

Waikato District Council operational response

Waikato District Council received varying test results today from its Ngaaruawaahia, Huntly and Te Kauwhata water treatment plants.

A sample submitted this week from Te Kauwhata water treatment plant showed a reading of 0.0054 mg/litre, well within Drinking Water Standards for arsenic levels of 0.01mg/litre.

A sample submitted this week from Huntly water treatment plant showed a reading of 0.0089 mg/litre, within Drinking Water Standards for arsenic levels of 0.01mg/litre.

But a slightly elevated reading of 0.012mg/litre was received from Ngaaruwaahia water treatment plant and was consistent with previous test results shared by Hamilton Council (0.0115) and Watercare (from its plant near Tūākau – 0.011).

Waikato District Council Waters Manager Keith Martin said the reason why test results varied was likely due to the fact the treatment plants operate differently.

“As of tomorrow, we will start injecting chlorine at the front end of the treatment process at the Ngaaruawaahia 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 is taking daily samples for testing from all plants that draw water from the Waikato River.

Hamilton City Council optimising treatment, commissioning new technology

Council’s latest sampling of treated water showed the water remains safe to drink, with arsenic levels broadly consistent with previous elevated readings. The sample showed a test result for arsenic of 0.0123 milligrams per litre of water, which represents an exceedance of the applicable Drinking Water Standard by 0.0023mg/litre.

Unit Director Three Waters Maire Porter said Council is taking two approaches to dealing with the form of arsenic currently being found in the Waikato 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.”

Maire Porter said Council anticipates the combined approach will 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 focussed on meeting all applicable Drinking Water Standards.”

Waikato Regional Council test results still to come

The results are not yet available for water samples collected from the Waikato River on Wednesday. The samples were taken from Lake Ōhakuri, Lake Arapuni, Karāpiro (upstream and downstream of the dam), Narrows Landing, Horotiu and Rangiriri.