A leading water treatment engineer says the Havelock North water contamination was preventable and the Government must take some responsibility for the outbreak.
Iain Rabbitts is angry the Hasting District Council's "uninformed" decision to not treat water for town supply and the Ministry of Health allowing it to happen has come at a grave cost.
Half of all households in the Hawke's Bay town have fallen ill as about 3200 people suffer from the violent waterborne illness.
Rabbitts said the outbreak reflected an "ostrich-like" approach to water supply and the risks involved.
"The potential for contamination of one of our untreated water supplies was telegraphed in 2000 when an E.coli outbreak in Canada killed five people and made 2500 people sick. It was only a matter of time before it happened here and this time Havelock North drew the short straw. It's pure luck it hasn't happened before."
Rabbitts said one person getting sick from drinking water was unacceptable and that someone may have died was appalling.
"I am so angry about this," said Rabbitts.
"We knew an incident was coming; it was just a matter of when."
Most shocking, he said, was the outbreak was preventable with relatively simple treatment.
"Whether the bacteria in question are E.coli or campylobacter doesn't really matter. What matters is that the water supply got contaminated by bacteria which could have been treated by chlorine. This is a simple, effective and common treatment for the removal of bacteria and viruses."
He said the chlorine stayed in the water along the pipes and in the reservoirs giving protection against downstream contamination.
Rabbitts said the Ministry of Health must also take some responsibility.
"They wrote the Drinking Water Standards for New Zealand and they wrote the Health (Drinking Water) Amendment Act 2007. They've allowed councillors to make uninformed decisions swayed by public opinion on the risks to a water supply. And they've allowed compliance with the Drinking Water Standards to be achieved by doing nothing."
Rabbitts said Havelock North - and several other areas - relied on the "do nothing" approach so problems were only discovered after contamination occurred and people started for get sick.
Rabbitts called for an "absolute minimum" of chlorine disinfection in all water supplies to prevent it happening again elsewhere in New Zealand.
"The Ministry of Health needs to lead the effort. They need to set deadlines and provide funding to enable the chlorination of all water supplies."
He said money being spent on hospital care for those who became violently ill would have been better spent on chlorinating the water.
He warned unless changes were made it was only a matter of time before contaminated water caused widespread sickness and hospitalisation in New Zealand.