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Chlorine Free Review results revealed

Published: 19 March 2021

Last Updated: 7 May 2021

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An independent review outlining the city’s drinking water infrastructure’s chlorine-free future versus the status quo will be presented to Napier city councillors next week.

The Review will be presented to councillors at the Sustainable Napier Meeting next Thursday, 25 March. Councillors will be asked to endorse the Review and approve the proposed Communications and Engagement Plan for the Review.

In December 2019, Council resolved to proceed with a review to consider the options for the future of Napier’s water supply, comparing the option of an enhanced system with chlorine disinfection against a safe chlorine free alternative. The Review began in June 2020.

Involving consultants across four countries as well as Napier City Council staff, the Chlorine-Free Drinking Water Review – Options for the Provision of Safe Drinking Water to Napier City, produced by Pattle Delamore Partners Ltd, and peer reviewed by GHD, identifies the complexities around providing this type of network, the potential costs, and how long it could it take.

The Review team refined a long list of options to consider the two most practical scenarios, and plotted these over a 20-year timeframe to compare the options’ costs against each other. 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.

The reviewers were not asked to provide a detailed cost analysis and have not undertaken design, however cost estimates indicate it will cost around $300 million over 20 years to achieve chlorine-free.

The Review 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, as there is no quick fix to enable Napier to return to chlorine-free in the short term. 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.

If the decision is made to go to chlorine-free, it could take until 2041 and cost an estimated $284 million.

These options will be part of the Long Term Plan 2021-31 (LTP) community consultation process. This includes a public meeting, Facebook Live Chats and Book a Chat with councilors, initiatives to inform the community of the Review’s findings and recommendations.

Napier Mayor Kirsten Wise is looking forward to sharing the findings with the community, and consultation through the Long Term process. “This will help us as a Council decide what our 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.”

The main issues related to the Review include: affordability, the ability of Council and industry to deliver the required work in a timely manner, and the new Drinking Water Standards NZ. These standards, while not approved yet, may force Council to deliver temporary measures to meet compliance which may defer the network’s long term development.


Why did we start adding chlorine to our drinking water?

Two of the main outcomes for Napier from the Havelock North Drinking Water Inquiry were:

  • the raising of bore heads above ground level to stop surface water from entering the bore and potentially contaminating the Water
  • chlorination of the pipe network following seven minor contamination issues in our reservoirs and pipe system since 2017.

The Inquiry made a number of recommendations to improve the safety of New Zealand’s water supplies and proposed changes to our Drinking Water Standards. The Government has identified that illness from public water supplies is significant, with up to 100,000 people getting sick every year. The uncomfortable reality is that New Zealand’s Water networks have probably been housing dangerous pathogens (bugs) for years.

Why does chlorine cause dirty water?

Our water source, the Heretaunga Aquifer, has naturally occurring manganese. When this water mixes with oxygen or chlorine, the manganese oxidises or changes state to manganese oxide, a black solid that can coat the inside of pipes. We use chlorine because it treats the Water for pathogens, and disinfects the pipes and reservoirs. Certain suburbs are affected more than others because of different water pressure and flow rates, and because there are higher levels of manganese in the bores that supply these suburbs. Tamatea and Parklands, which have had more dirty water incidents than other parts of Napier, are in the process of being ‘ring-fenced’ off from the rest of the network. These suburbs will then be supplied with lower manganese water from the Taradale bores to see if this improves water quality.

Can we just switch it off?

We are legally required to provide safe and clean drinking water, so if we switched it off with no change to the way we manage risks we would be non-compliant and could face enforcement action.

Why has the Review taken so long?

A robust two-stage procurement process was followed, including a Registration of Interest, followed by a shortlisted subgroup providing a proposal to Council. Following the tender panel review of submissions, four consultants were shortlisted to proceed to the second stage. This occurred at the same time as the first COVID-19 lockdown, which delayed the process by around a month. Council approved the recommendation for Pattle Delamore to complete the Review in May 2020. The complexity of the Review meant it could not be rushed. It included: site visits, a review of current water-related strategies, comparisons with overseas chlorine-free systems and what they have in common, government agencies, community representatives, and a peer review process.

If Christchurch can do it, why can’t we?

The government has stated that all suppliers will need to have a “disinfection residual” i.e. chlorine disinfection, to assist with managing network risks in their supplies. The new regulator, Taumata Arowai, will be in place by 1 July 2021 and they will be involved decision making around an exemption process that has been allowed for in the Water Services Bill. Council currently has an approved Water Safety Plan that identifies how we intend to manage
the public health risks in our supply. Chlorine is identified as one of the barriers to contamination that Council will maintain to keep us all safe. In discussion with senior health officials during the Review, it was clear a high bar would be set before we could go safely chlorine-free and to get an exemption from compulsory chlorination. The Review has shown that there is a lot of work to be done on our network, monitoring and Systems, even with chlorine in place. Christchurch will be subject to the same rules and although some of their supplies are currently not chlorinated, potentially this will not continue, given the new regulations.

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