Council's collective knowledge and expertise on water supply is much greater than it has ever been, and it continues to grow. Photo / Getty Images
COMMENT
Napier City Council would like to comment on the information provided in Monday's Talking Point by the Guardians of the Aquifer.
We would like to share with our community a little about the project team for our Safe Chlorine-Free Drinking Water Review, and its brief.
The project team includes NCC staff, consultants Pattle Delamore, and independent international experts, including two world-renowned professors, one of whom helps manage a chlorine-free water supply for Amsterdam.
Our Water Team collectively has a wide range of skills and experience in New Zealand and overseas in the water industry, supported by a long-serving depot team who have extensive knowledge of the network.
Our team also engage with highly qualified consultants in specialist areas to assist us with our plans for the modernisation of our water infrastructure.
Council's collective knowledge and expertise on water supply is much greater than it has ever been, and it continues to grow.
Our responsibility is to provide safe drinking water that meets our legal obligations and minimises the risk to public health – the community – particularly those who are the most vulnerable.
The legislation is evolving, and as it does, so will our responsibilities. As a result, how the water network used to be operated is no longer appropriate.
The project team's primary responsibility is to provide an independent and fair review of what we have to do to meet legal obligations both with chlorine and without.
The team has been working with the Ministry of Health (MoH), Taumata Arowai, which is the new Water Services Regulator set up by Government, and other industry professionals to determine the likely requirements for us to achieve an exemption from mandatory disinfection.
Turning chlorine off is not possible in 2020 – we are not legally able to do this without demonstrating risks to the supply have been sufficiently mitigated.
The point of the review is to identify how the risks can be mitigated, and what the costs and timeframe to achieve exemption could be.
The MoH has indicated it is likely our operational bores will lose secure bore status, at which point we will have to begin UV treatment.
An additional barrier, such as UV treatment, is necessary to minimise contamination risk.
No decisions have yet been made on how many chlorine-free options will be presented to council, no recommendations or conclusions reached. However, five different chlorine-free options have been included in the review.
Regarding disinfection byproducts (DBPs) – what is left behind as part of the disinfection process – DBPs do not form by just adding chlorine to water. There are a number of other factors, none of which appear to exist in our system.
Our sampling has shown that concentrations of regulated DBPs cannot be detected, which indicates there is no DBP problem in Napier's water supply.
We also have to consider how we can remove iron and manganese from our water supply, since they can contribute to the formation of biofilms and dirty water. Treatment is likely to be required to remove these elements, with or without chlorine.
Chlorine acts as a primary disinfectant, removing bacteria and viruses and to a lesser extent Giardia. Residual chlorine (that which remains in the water within the network) protects against contamination arising from minor forms of contamination entering our network, and small backflow events.
Backflow is not just about contamination, although that is important. Chemicals such as pesticides and herbicides can also enter the system.
There was also a reference to transgressions, which is where you have a positive result for E. coli in a water sample. Five transgression events, not one, were detected in Napier's water supply in 2017.
Council worked with the MoH and Drinking Water Assessor (DWA) throughout this time, and when disinfection was introduced.
A result that confirms E. coli and/or coliforms are detected confirms a contamination event has occurred, regardless of the number of E. coli recorded. The testing regime is consistent with the NZ Drinking Water Standards and MoH requirements, and is not overly sensitive.
We have 10 recommendations regarding water, which will go forward to the council meeting next week at which the Annual Plan 2020/21 is expected to be adopted.
The most important of these was reconfirming that water is council's number one priority.
The review has several more steps to be completed before it is taken back to council, including an external peer review, and an internal review of the financial impacts of the proposed work programme.
Any final chlorine-free option also needs to be approved via a new Water Safety Plan, and currently there is no Government approved pathway to exemption.
The project team is working with the appropriate parties to ensure we have the best chance of achieving exemption if the community and council decide chlorine-free is the best way forward