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We manage four water treatment plants in the Wellington metropolitan area on behalf of Greater Wellington Regional Council who own the treatment plants.  

These are:

  • Te Marua Water Treatment Plant
  • Wainuiomata Water Treatment Plant
  • Waterloo Water Treatment Plant
  • Gear Island Water Treatment Plant

We add fluoride to the water at all four of these treatment plants. 

Our aim is to maintain a steady level of fluoride in the water at our treatment plants that meets the Ministry of Health fluoride target of 0.7 – 1.0ppm. This is the amount recommended by the Ministry of Health and the World Health Organisation to provide protection against tooth decay.

We also have controls in place to ensure we never supply consumers drinking water over the Maximum Acceptable Value (MAV) of 1.5ppm.

Stopping fluoride at Te Marua and Gear Island Water Treatment Plants

In 2021, we stopped our fluoride facilities at the Te Marua Water Treatment Plant in May and at the Gear Island Water Treatment Plant in November due to operational and health and safety issues, which meant we could not guarantee that we could add fluoride safely. At the time we didn’t tell anyone we did this, and we apologise for that and the concern caused.

In March 2022, we announced that the fluoride facilities at both Te Marua and Gear Island have been stopped but we provided people with an incorrect date for when we stopped fluoridation at the plants, which we corrected the next day. Again, we acknowledge that this falls short of the expectations of our customers and communities, and we apologise for the concern caused.

Independent inquiry

To fully understand why the fluoride facilities were turned off at the Te Marua and Gear Island Water Treatment Plants and why our customers, community, Councils and our Board were not told of this in a timely and accurate manner, the Wellington Water Board has commissioned an independent inquiry.

This inquiry is currently underway and being led by Doug Martin of Martin Jenkins. The inquiry is expected to take eight weeks to complete.

Once completed, and the Board has the final report, findings from the inquiry will be made public as well as what action the Board will take to ensure this doesn’t happen again.

Read the Terms of Reference for the independent inquiry here.

Fluoride Dosing & Measurement at Water Treatment Plants

Wellington Water has sensors for monitoring the level of fluoride in the water at each of the four metropolitan Wellington drinking water treatment plants. These readings are taken automatically. The daily averages per plant are calculated (using an arithmetic mean method) and provided monthly to Ministry of Health.

Listed below are the percentages and monthly average that the plants achieved for the month of May 2022.

Water Treatment Plant

Areas Supplied

Percentage met

(portion of readings within Fluoride target)

Average Dose (ppm)

Comments

Te Marua

Upper Hutt, North and West Wellington

0%

0.09

Not dosing

Waterloo

Hutt City, CBD, Eastern-Southern Wellington (excl. Petone, Stokes Valley)

100%

0.80

-

Gear Island (taken at the supply main)

CBD, Eastern-Southern Wellington Only

0%

0.40

The low dose of fluoride showing up in the water being tested at Gear Island is because water being supplied to Wellington is a mix of water from both Wainuiomata and Waterloo, which contains some fluoride in it. Under normal circumstances this water would then be topped up with fluoride to the necessary level at Gear Island

Wainuiomata

Wainuiomata township, Eastern-Southern Wellington

97%

0.80

-

Other Drinking Water Analysis

To comply with drinking water quality requirements, Wellington Water also performs additional chemical analysis on the water leaving treatment plants. This analysis is performed by Eurofins, which is an independent IANZ-accredited laboratory.

The annual chemical analysis summary is available here.

 

Restoring fluoride at Te Marua and Gear Island Water Treatment Plants

We are committed to getting our fluoride facilities up and running at the Te Marua and Gear Island Water Treatment Plants as soon as possible so long as it safe to do so. This work is already underway.

We have outlined our programme of work to achieve this. 

As part of this work, we are also looking at improvements to the fluoride facilities at the Waterloo and Wainuiomata Water Treatment Plants to improve the consistency and reliability of fluoride levels at these plants.

Click on the sections below for an update on the work we are doing on the fluoride facilities at each plant.

Related documents

Te Marua Water Treatment Plant

The fluoride facility at the Te Marua Water Treatment Plant was stopped in May 2021 due to operational and health and safety issues, which meant we could not guarantee that we could add fluoride safely.

We have had ongoing issues with being able to source a type of fluoride product that was most suitable for the equipment at the plant. These issues have now been resolved and a more suitable product is available and in use by us across our other facilities.

We are dealing with a range of factors at Te Marua before we can safely get fluoride back up and running at the plant. These are:

  • Aging fluoride dosing equipment that needs updating.
  • A damaged baffle curtain, which works by slowing down the flow of water, allowing the fluoride powder time to mix to give operators more control of the mixing ratio.
  • Checks and investigation of the entire operation of the current facility. 

We are replacing the current facility with a new standalone fluoride facility at Te Marua and work is underway to construct this.

To do this we have ordered key components and equipment from overseas and, provided there are no international supply chain issues, we are aiming to have fluoride back on in the drinking water in Te Marua in September 2022.

In the meantime, we continue to investigate the existing fluoride facility at Te Marua to determine if it can be safely switched back on while the new facility is being constructed.  

 

Project progress update – Friday 1 July 2022

This week we have completed the ground works for the foundations for the new standalone fluoride facility. We have now started installing the pipes for the new facility and we have completed our design work.

We continue to source and buy components for the new fluoride facility.

Project progress update – Thursday 23 June 2022

Progress on the ground works for the foundations for the new standalone fluoride facility were again hampered by bad weather this week. However, we’re still expecting to be on track in terms of the overall delivery timeframe.

Our design work is progressing well. We continue to source and buy components for the new fluoride facility.

The new baffle curtain has been successfully installed in the treated water reservoir this week in line with the project schedule.

 

Gear Island Water Treatment Plant

The fluoride facility at the Gear Island Water Treatment Plant was stopped in November 2021 due to operational and health and safety issues, which meant we could not guarantee that we could add fluoride safely. 

The fluoride dosing system at Gear Island is also aging and will be replaced with a new standalone fluoride facility.

To do this we have ordered key components and equipment from overseas and, provided there are no international supply chain issues, we are aiming to have fluoride back on in the drinking water in Gear Island in September 2022.

 

Project progress update – Friday 1 July 2022

This week we have completed the ground works for the foundations for the new standalone fluoride facility. We have now started installing the pipes for the new facility and we have completed our design work.

We continue to source and buy components for the new fluoride facility.

Project progress update – Thursday 23 June 2022

Progress on the ground works for the foundations for the new standalone fluoride facility were again hampered by bad weather this week. However, we’re still expecting to be on track in terms of the overall delivery timeframe. 

Our design work is progressing well. We continue to source and buy components for the new fluoride facility.

 

 

 

 

 

 

 

 

Wainuiomata Water Treatment Plant

The fluoride facility at the Wainuiomata Water Treatment plant remains operating.

We have had ongoing issues with being able to source a type of fluoride product that was most suitable for the equipment at the plant. These issues have now been resolved and a more suitable product is available and in use across our other facilities.

 

Project progress update – Friday 1 July 2022

The fluoride facility continues to dose and is operating well.

Project progress update – Thursday 23 June 2022

The fluoride facility continues to dose and is operating well.

 

 

 

 

 

Waterloo Water Treatment Plant

The fluoride facility at the Waterloo Water Treatment Plant remains operating. We are currently dosing fluoride at this plant.

We have had ongoing issues with being able to source a type of fluoride product that was most suitable for the equipment at the plant. These issues have now been resolved and a more suitable product is available and in use across our other facilities.

 

Project progress update – Friday 1 July 2022

Planning is underway for a full shutdown of the fluoride facility in August to carry out minor renewals and maintenance.

Project progress update – Thursday 23 June 2022

We have a full shutdown planned in August, to carry out minor renewals and maintenance.

 

 

 

 

Previous Fluoride Dosing & Measurement at Water Treatment Plants

The percentages and monthly average that the plants achieved for the month of May 2022.

 

Water Treatment Plant

Areas Supplied

Percentage met

(portion of readings within Fluoride target)

Average Dose (ppm)

Comments

Te Marua

Upper Hutt, North and West Wellington

0%

0.06

Not dosing

Waterloo

Hutt City, CBD, Eastern-Southern Wellington (excl. Petone, Stokes Valley)

94%

0.80

-

Gear Island (taken at the supply main)

CBD, Eastern-Southern Wellington Only

0%

0.35

The low dose of fluoride showing up in the water being tested at Gear Island is because water being supplied to Wellington is a mix of water from both Wainuiomata and Waterloo, which contains some fluoride in it. Under normal circumstances this water would then be topped up with fluoride to the necessary level at Gear Island

Wainuiomata

Wainuiomata township, Eastern-Southern Wellington

97%

0.84

-

 

The percentages and monthly average that the plants achieved for the month of April 2022.

 

Water Treatment Plant

Areas Supplied

Percentage met (Portion of readings within Fluoride target)

Average Dose (ppm)

Comments

Te Marua

Upper Hutt, North and West Wellington

0%

0.06

Not dosing

Waterloo

Hutt City, CBD, Eastern-Southern Wellington (excl. Petone, Stokes Valley)

93%

0.78

-

Gear Island (taken at the supply main)

CBD, Eastern-Southern Wellington Only

0%

0.3

The low dose of fluoride showing up in the water being tested at Gear Island is because water being supplied to Wellington is a mix of water from both Wainuiomata and Waterloo, which contains some fluoride in it. Under normal circumstances this water would then be topped up with fluoride to the necessary level at Gear Island

Wainuiomata

Wainuiomata township, Eastern-Southern Wellington

80%

0.72

We were only able to dose reliably for 80% of the time at the Wainuiomata WTP in April due to the WTP having to shut down for a period as a result of insufficient water in Wainuiomata river.

 

 

Data Usage Disclaimer

Wellington Water aims to ensure the data published on this page is accurate and up to date. Wellington Water does not accept any responsibility for the use of or reliance on the data and shall not be liable to any person on any ground for any loss, damage or expense arising from such use or reliance.