The Government has ordered a rapid review into the health response to lead being discovered in the water supply for two east Otago towns.
Karitane and Waikouaiti residents were told last Tuesday they must not use the tap water as lead had been discovered in the reservoir.
A high lead level sample was taken in Waikouaiti in December and emailed to a council staffer - but they were on holiday so didn't see the email until they got back in the new year.
One of the samples had 40 times the acceptable amount of lead.
Associate Health Minister Ayesha Verrall has ordered a rapid review into the health system response.
"New Zealanders have every right to expect that their drinking water is safe. What's happened in Otago is unacceptable," Dr Verrall said.
The review to be led by Director-General of Health Ashley Bloomfield and independent experts will be carried out to ensure public confidence in the health response, she said.
"While it is vital that we understand how levels of lead-contaminated the water, we also want to review our overall health response to the situation. 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.
"Ultimately, we want to reduce the risk of this happening again and inform the ongoing response.
"I expect the Director-General to report back to the Government on the preliminary findings and suggested actions by March," Dr Verrall said.
This week residents in the affected areas can get a free blood test to see if the lead in the water has affected them. On the first day of testing on Tuesday, 282 people turned up.
Karitane mother of three Jazhr Hansen took her five-month-old baby to get tested.
"I'm happy the Government is looking into this and taking it seriously and they're not just forgetting about it. It's a big deal what's happened.
"We have the right to clean water for our children and ourselves.
"The whole thing has been handled really badly - there has been a lot of finger-pointing, there's a lot of shifting blame which just makes people confused," Hansen said.
Dunedin City Council chief executive Sandy Graham said preliminary results of water testing done late last week had shown low or non-detectable levels of lead in the water supply.
The latest water results were encouraging, but it was important to wait until all blood test results were in, and the results across the population were analysed, before drawing conclusions, Graham said. The council is still investigating what caused the spike in lead levels - work so far has confirmed the presence of lead joins in the very old cast iron pipes in the Waikouaiti network.
"While the joins have not been confirmed as the source of the intermittent significant spikes, work to replace the pipes has begun," Graham said.
"We expect to replace about 4km of pipes as a result over the next few months and replace the old sections with temporary above-ground water pipes," she said.
Graham said the council is looking at moving to online monitoring of raw water quality which would give faster results and allow the water supply to residents to be cut at short notice should further spikes occur.