The Government is launching a rapid review into the health response after high levels of lead were discovered in the water of two Otago towns months before residents were made aware.
Mass voluntary blood testing is underway for Waikouaiti and Karitāne residents to determine if they have been chronically affected by exposure to the metal in their drinking water.
They were only told last week to stop using tap water, despite elevated levels being detected almost six months ago, and a high level sample being taken in December.
Residents are currently being provided with tankered drinking water until authorities get to the bottom of the problem.
Associate Health Minister Ayesha Verrall this morning told Breakfast she agrees it is not acceptable.
"We need to be able to all have confidence in the safety of our water supply and that's why the Government has initiated the three waters reform," she said.
"That is a really big project because there has been decades of underinvestment in the water infrastructure in New Zealand.
"Minister [Nanaia] Mahuta is leading the way with over $700 million of investment in the future in our water supply and also clearing up some relationships with some of the regulators by setting up and independent water regulator that will monitor standards and guide the response to events like these."
The source of the contamination in Otago has not been identified and it is not clear when these spikes in lead concentration started. It is currently under investigation by Dunedin City Council.
The independent review will look into how the health system, including local and central government health agencies, responded to the situation and how the risk to public health was subsequently addressed.
Findings are expected to be revealed next month.