Norsewood Water Programme of Works
Tararua District Council is undertaking a programme of investigations, maintenance activities and planning work to address ongoing water quality issues within the Norsewood water supply network.
Monitoring has identified manganese levels above the acceptable value within the water supply. Council has already invested in upgrades to the Norsewood Water Treatment Plant to improve water quality. While these improvements have helped, monitoring has shown that manganese levels within the network remain above the acceptable value. Current public health advice indicates there is no immediate health risk for the general population.
Testing has confirmed the Norsewood Water Treatment Plant is producing compliant drinking water, investigations indicate some of the remaining water quality issues are linked to historic deposits and ageing infrastructure within parts of the reticulation network. Council is working with Taumata Arowai to address these issues and improve water quality outcomes for the Norsewood community.
About manganese
There have been recordings at some of our sampling points in Norsewood where Manganese levels have exceeded the maximum acceptable value.
Manganese is a naturally occurring mineral that can be found in many water sources. Elevated levels can occur when water has been sitting in parts of the network for an extended period or in areas with low flow. Short-term exposure to water with manganese levels above the mandatory standard is not generally a risk to health. However, too much manganese over a long period of time may negatively affect human health.
It can also cause discolouration or staining of water and is generally considered an aesthetic issue.
For information about manganese and potential health considerations, see the guidance of the Water Services Authority - Taumata Arowai: Manganese | The Water Services Authority - Taumata Arowai
What this means for you
Current public health advice indicates there is no immediate health risk for the general population, and you can continue to use your water as normal.
If you have specific health concerns, particularly regarding bottle-fed infants or someone with a medical condition, please consult your healthcare provider.
We are continuing to communicate about manganese while it remains an issue, in line with requirements from the Water Services Authority – Taumata Arowai.
What we are doing
Council is undertaking a range of activities to better understand the issue and identify the most effective long-term solution.
These activities include:
- Additional water quality monitoring and sampling.
- Maintenance activities and optimisation at the Water Treatment Plant, including cleaning of filter media.
- No-Des network flushing to remove deposits from water mains.
- Investigations into the condition of the water network.
- Planning for future reticulation upgrades.
- Gathering information about existing property connections to support future project planning.
Current status
The programme is currently in the investigation and planning phase.
Before any major physical works can begin, Council needs to better understand the condition of the network and how individual properties are connected to the water supply. This information will help ensure future investment is targeted effectively and minimises disruption to residents.
Property surveys and engagement with affected residents are currently being prepared as part of this work.
Previous works
Council has already invested in upgrades to the Norsewood Water Treatment Plant to improve water quality. While these improvements have helped, monitoring has shown that manganese levels within the network remain above the acceptable value.
Previous Norsewood Water Treatment Plant upgrades
Current investigations indicate some of the remaining issues are related to the reticulation network rather than the treatment plant itself. Council is now focused on identifying and addressing those causes through further investigations, maintenance activities and planning for future upgrades.
Planned network improvements
Council is investigating a programme of network improvements that may include:
- Replacement of customer water service connections.
- Renewal of water mains.
- Installation of modern backflow prevention devices.
- Targeted repairs to ageing infrastructure.
- Realignment of some network assets.
No final decisions have been made on the timing of major construction works. Further information will be shared as investigations progress.
FAQs
Council has already invested in upgrades to the Norsewood Water Treatment Plant to improve water quality. While those improvements have helped, ongoing monitoring has shown that manganese levels within the network remain above the acceptable value. Council is now undertaking a programme of investigations, maintenance activities and planning work to address ongoing water quality issues in the Norsewood water supply and improve the long-term reliability and resilience of the network.
The Norsewood Water Treatment Plant is producing drinking water that meets regulatory requirements. However, manganese levels in parts of the network remain above the acceptable value, and Council is working with Taumata Arowai to address the issue and improve water quality outcomes.
Manganese is a naturally occurring mineral that can be found in many water sources. Elevated levels can occur when water has been sitting in parts of the network for an extended period or in areas with low flow. Short-term exposure to water with manganese levels above the mandatory standard is not generally a risk to health. However, too much manganese over a long period of time may negatively affect human health.
For more information on manganese, head to: Manganese | The Water Services Authority - Taumata Arowai
Investigations indicate that historic deposits and ageing infrastructure within parts of the distribution network are contributing to elevated manganese and iron levels as water moves through the system. Current investigations suggest the issue lies within parts of the network rather than the treatment plant itself.
Council has already invested in upgrades to the Norsewood Water Treatment Plant to improve water quality. While those improvements have helped, ongoing monitoring has shown that manganese levels within the network remain above the acceptable value. Investigations now indicate that some of the remaining issues are linked to historic deposits and ageing infrastructure within parts of the reticulation network, rather than the treatment plant itself. Council is continuing investigations, maintenance activities and planning work to identify and implement the most effective long-term solution.
For more information on the previous Norsewood Water Treatment Plant upgrade, head to: Norsewood Water Treatment Plant Upgrade | Tararua District Council
Council is undertaking additional optimisation, sampling and monitoring, planning network improvement works, carrying out maintenance activities at the treatment plant, and investigating sections of the network that may be contributing to water quality issues. Council is also developing options for future infrastructure upgrades.
No-Des flushing is a method of cleaning water pipes that helps remove sediment and deposits from the network. It is being considered as an interim measure to help improve water quality while further investigations and long-term solutions are developed.
An acid wash is a cleaning process used on the filter media at the treatment plant to remove accumulated manganese particles and improve the effectiveness of the filtration process.
Additional sampling will help Council better understand where water quality issues are occurring within the network, measure the effectiveness of improvement activities, and inform future decisions about network upgrades.
Council is currently investigating and planning a programme of network improvements that may include replacing water service connections, renewing water mains, installing modern backflow prevention devices and undertaking targeted repairs to network infrastructure. No major construction works have started at this stage.
Council needs a clear understanding of how properties are connected to the water network before any future upgrade works are designed and delivered. This information will help minimise disruption and ensure properties remain connected appropriately.
Some property owners may be contacted as part of future surveys or investigations to help Council understand existing water connection arrangements. Any access requirements will be discussed with property owners beforehand.
Some maintenance and future upgrade activities may require temporary interruptions to water supply. If this occurs, affected residents will be notified in advance wherever possible.
Council is currently working through investigations and planning to identify the most effective long-term solution. Timeframes for any major upgrade works will be communicated once planning is further advanced.
Taumata Arowai is New Zealand's water services regulator. Council is working with Taumata Arowai to ensure appropriate steps are taken to address water quality issues and improve outcomes for the Norsewood community.