KEY POINTS:
Clean drinking water will be guaranteed under a new law - but there are warnings householders in small towns and rural areas will pay more in rates and water charges as a result.
The Health (Drinking Water) Amendment law allows for drinking water standards which all water suppliers must take "reasonable and practicable steps" to meet.
Health Minister Pete Hodgson said the drinking water standards law was in line with other OECD countries, and important for both health and New Zealand's international image.
However, the law change has hit the Far North District Council with a bill of up to $10 million to upgrade its equipment - and others have estimated costs of up to $30 million, which would have to be passed onto householders in rates or water charges.
Local Government New Zealand has estimated the cost of meeting the law to provincial councils will tally up to $600 million in upgrades and $31 million a year for operational costs.
LGNZ manager of development Geoff Swainson said the law would have little effect on urban centres, which already largely complied with the requirements.
"But just about every non-urban council will have to do something significant, and the rule of thumb is the more rural and provincial a council is, the more problems they will have."
The National Party opposed the law because of the extra costs it put on small towns and rural areas.
However, Mr Hodgson said Government funding of $150 million would help both councils and private suppliers comply.
Mr Swainson said the law was "unnecessary and unwarranted" as most councils were already working to meet voluntary standards set by the Ministry of Health.
The new law could also catch some out unawares because individual homes with their own tanks are not covered, but any water supply which goes to more than 25 people for at least two months a year has to comply.
This could capture community-run schemes in which a small group of houses run their own supply, as well as rural marae and schools or businesses which use tank water.
Mr Hodgson said the affordability of upgrades was one consideration taken into account when supplies were checked to see whether all practicable steps had been taken.
Those in charge of small water supplies also had longer to comply - while major suppliers come under the law in 2008, others are staggered with the smallest coming in 2013.
Rick McCall, a spokesman for Far North District Council, said the law required it to carry out upgrades on its nine water treatment plants, costing up to $10 million, which could be passed on in water charges.
"We think the legislation is a bit arbitrary in its requirements and most of the cost we are facing is not in lifting water quality, but in better monitoring systems."
He said the monitoring requirements were "a bit extreme" and did not have the flexibility needed.
Whangarei District Council spokesman said the council had just spent more than $1 million on upgrades of its plants to pre-empt the law, and was satisfied it was compliant.
Estimated Costs
* Up to $30 million for householders in rates or water charges
* Up to $600 million for councils in upgrades