A return to chlorine-free water in Napier could take 20 years and close to $300 million, if councillors decided they wanted to remove it, a report has found.
Chlorine was added to Napier's water supply in 2017 after E. coli was detected in the pipe system.
Since then complaintsto Napier City Council about dirty, discoloured water have increased tenfold, as the chlorine reacts with manganese in Napier's ageing pipe system.
Few areas of the city have been spared from the malaise and almost every councillor to be elected to Napier City Council in 2019 did so vowing to relook at whether it was possible to remove it.
A review investigating the removal of chlorine was ordered last year and completed by engineering and environmental consultants, Pattle Delamore Partners Ltd, which put forward three options.
After years of "historically low levels of investment", each option details significant infrastructure upgrades over the next 20 years.
The road to chlorine-free is the most costly of the three, totalling $295m in spending and requiring strong community support.
A staged process, it involves NCC moving to two new consolidated bore fields and installation of water treatment plants where manganese and iron can be removed and UV light used to treat it.
Improving the network will involve an "aggressive mains replacement programme" - 150km of pipeline replaced over 10 years, many of which are made from cast-iron and asbestos concrete known for causing leaks.
Backflow prevention devices and SMART water meters would also be installed in 23,000 homes with the goal of getting a chlorine exemption from Taumata Arowai (the water regulator) by 2043.
This would be at an ongoing cost of $5.6m each year thereafter.
A $216m option adopts a similar approach and aggressive replacement programme, leaving the door open to exploring chlorine-free at a later date.
However, the report states the aggressive pipe replacement programme may not be feasible and a more realistic rate may only see the city chlorine-free by 2057.
A third $178m option would improve water quality to meet new regulator standards, but would continue to involve chlorination.
The report does not identify a preferred option but shows how the investment of the current Long Term Plan and an enhanced network are stepping stones towards a chlorine-free future.
It recommends a staged approach, to make sure the city's drinking water supply continues to be safe throughout these changes, over a number of years.
"There is no quick fix to enable Napier to return to chlorine-free in the short term," a Napier City Council spokesperson said.
"For Napier to develop a chlorine-free supply that would be likely to meet the new regulator's standards, the network and its operation would require considerable enhancements, moving towards the advanced chlorine-free networks seen overseas."
The three options in the review will be presented to councillors at the Sustainable Napier Meeting next Thursday, March 25, and will form of the Long Term Plan 2021-31 (LTP) community consultation process before council makes a decision.
This will include a public meeting, Facebook Live Chats and Book a Chat with councillors, initiatives to inform the community of the review's findings and recommendations.
Napier Mayor Kirsten Wise said community feedback would help the council decide what its next steps will be.
"Keeping the upcoming central government Three Water reforms in mind, the future of our drinking water supply is one of the most important decisions this council will make."
Councillor Richard McGrath said since millions of dollars are going to be spent on Napier's water anyway, it's up to the community to decide whether NCC should "look at going the full hog", to get chlorine-free.
He added that council have a plan in place to get the dirty water sorted.
"Apparently we can filter out the manganese and all will be good. That's something we can do a little bit quicker [and at less cost]," McGrath said.
Fellow councillor Keith Price said the combination of the chlorine and manganese is the real problem, rather than the chlorine itself.
"That [reaction creating dirty water] I think concerns a lot of people more than the chlorine does," he said.
Price said it was a good thing the report had been done, so now everyone can see exactly how much it would cost to get chlorine-free.
"It is a biggie as far as time goes and expense," he said, adding that he was not surprised.
The news was a shock to Pauline Doyle of the Guardians of the Aquifer group, who has campaigned against chlorination.
"It is disheartening to read the headlines claiming it will cost $300m and take two decades, if ever, for Napier to go chlorine-free.
"Ratepayers will now be fearful of a massive rates rise and could give up on the hope of ever tasting pure, chlorine-free water in Napier."
Doyle said she felt the report overstated the amount of work required and that the estimated cost to qualify for exemption from mandatory chlorination has been grossly inflated.