Regulations for many suppliers took effect in November last year, but insistence on compliance has ramped up in recent weeks amid a Cryptosporidium outbreak in Queenstown.
As of yesterday, the number of confirmed cases of illness was 61.
Councils had until last night to provide updated information to national water regulator Taumata Arowai (TA) about where they stood on installation of protozoa barriers.
The Otago Daily Times yesterday asked southern city and district councils for the same information.
The Dunedin City Council confirmed it had protozoa barriers at all its water treatment plants.
Full compliance has not yet been demonstrated to the ODT by any other council in the South.
Water schemes in the Queenstown Lakes District operating without a protozoa barrier are Queenstown, Wānaka, Luggate, Glenorchy, Wānaka Airport and Corbridge.
TA served a compliance order to the council on September 20 regarding two Queenstown plants and boil-water notices were issued.
"Since the current crypto outbreak, we have expanded our monitoring and testing in line with the requirements of the compliance order," a council spokesman said yesterday.
"More details about the investment required to install protozoa barriers at all remaining council-managed water supplies will be shared once the current compliance order has been met and, at the latest, as part of the upcoming long-term plan process."
The Central Otago District Council shared information that implied tens of millions of dollars might have to be spent there on water upgrades, although this would not just be related to protozoa.
Protozoa barriers were lacking at Cromwell, Patearoa, Ranfurly and Omakau.
A new water treatment plant is planned for Cromwell and an investigation into this has been running for three years.
Building a new treatment plant at Omakau could cost $20 million-$25m, and another at Ranfurly a further $20m-$25m.
The Clutha District Council said TA had identified one scheme, Tuapeka West, as lacking a protozoa barrier and it was on a boil-water notice.
This would likely remain until replacement of the scheme by the new Greenfield rural drinking water scheme next year.
The Greenfield project has an estimated overall cost of $20m.
"However, the new scheme will address more than just the issue of a lack of protozoa barrier at the Tuapeka West scheme," council acting chief executive Sharon Jenkinson said.
"It will improve reliability in the provision of quality drinking water to the Balmoral, Tuapeka and Lawrence water schemes through a new bore source and the amalgamation of pipe networks."
Gore District Council threewaters operations manager Aaron Green said the council treated for protozoa at its East Gore and Mataura plants, but not Hilbre Ave, which supplied water to about 35% of Gore properties.
"The council is currently undertaking a project to centralise its water treatment at the East Gore plant, which will ensure everyone in Gore gets water treated to national drinking water standards."
