The country's top health official says the Ministry of Health may have to take a stronger approach to ensuring water suppliers provide safe drinking water in New Zealand.

Director General of Health Chai Chuah took the stand as the Havelock North water inquiry continued yesterday and was asked whether he thought the current level of non-compliance with drinking water standards were acceptable.

Counsel assisting the inquiry Nathan Gedye drew his attention to Ministry of Health figures from 2009 to 2015/16 showing there are still 759,000 people (20 per cent of the serviced population) being supplied water that was not demonstrably safe to drink.

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Of these, 92,000 were at risk of bacterial infection, 681,000 of protozoal infection and 59,000 at risk from the long-term effects of exposure to chemicals.

Mr Gedye asked if Mr Chuah was troubled by these numbers and the fact there had been very little if any improvement over the years.

Mr Chuah said he had not realised the numbers were that high until seeing the figures yesterday and agreed the figures were troubling.

"There's no question that the Stage One findings of the inquiry have shown a number of things the ministry should expedite and this is one of those things.

"Clearly with the lack of progress we will have to re-examine our approach around trying to support [drinking water suppliers] and address why we seem not to be making the progress we would like to be."

When it was pointed out that in England and Wales, compliance rates of 99.9 per cent were reached, he said that was a benchmark the ministry should set itself in New Zealand.

The fact there had been five E. coli exceedances in Napier's drinking water supply since February this year was also raised, and that the inquiry had been told there was a reluctance to continue chlorination of the Napier system.

"That's something that would concern me - we would look at how local public health officials are engaging with drinking water suppliers - strong leadership would be beneficial," Mr Chuah said.


He was also questioned about evidence presented to the inquiry that there was a shortage of Drinking Water Assessors in New Zealand, they were not appropriately qualified and took too much of a "softly, softly" approach to enforcing drinking water compliance.

Mr Chuah said he would need to receive advice from his officials and would be receptive to making changes to address deficiencies of people working in the system.

"My understanding from ministry staff is we have powers to act and enforce and we would support DHB health officers to enforce, but there are a number of steps that would need to be checked off and cleared before we go to enforcement.

"The statistics being presented show that maybe there should be a supportive but stronger approach."

He agreed it was something that could be looked at before the final inquiry report came out in December.

"If there are things that should be expedited that I can do with my powers and working with the community and industry there's no reason why we should slow it down."