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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.

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 commissioned an independent inquiry in March 2022.

The inquiry was undertaken by Martin Jenkins and completed in late June 2022. The Board received and accepted all the inquiry’s recommendations in early July 2022.

A programme of work is now underway to implement the recommendations.

Fluoride levels & 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 July 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%

0.05

Not dosing

Waterloo

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

97%

0.80

-

Gear Island (taken at the supply main)

CBD, Eastern-Southern Wellington Only

0%

0.37

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

89%

0.75

The fluoride facility at Wainuiomata was turned off over a three day period this month to allow for unfluoridated water to be supplied to Petone and Korokoro
while urgent repairs to a bulk water pipe on Waione Rd, Petone were being undertaken.

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 have been working at pace to safely restore fluoride at the Te Marua and Gear Island Water Treatment plants, which will be back on in September 2022.

We have received one-off funding from the Greater Wellington Regional Council to construct standalone fluoridation facilities at both plants.

On 29 July 2022 we announced that we would start testing the new fluoride facilities at both plants before bringing the facilities into full service.

Once testing has started, fluoride levels will be steadily brought up to the Ministry of Health target range during August.

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 12 August 2022

Testing of the new fluoride facility started this week. This involved running water through the system and checking the controls, which needs to be completed before we start to add fluoride into the drinking water next week.

We will start to add fluoride at low levels first and steadily bring it up to the Ministry of Health target range over the coming month.

During this period the fluoride facilities may also be turned off and on to allow us to fine tune and adjust as required.

We remain on track to have the new facility fully operational in September.

 

Project progress update – Friday 5 August 2022

The container, which the new facility will be housed in, and the bulk tank, which will contain the fluoride, have now been built, are onsite, and have been fixed into position.

The team are continuing to work hard to make the final piping and electrical connections so that we can begin testing the new facility next week. We have been delayed a little with the effects of COVID and we are still waiting on some remaining components.

Once testing has started, fluoride levels will be steadily bought up to the Ministry of Health target range. However, during this period the fluoride facilities may also be turned on and off to allow us to fine tune and adjust as required.

We remain on track to have the new facility fully operational in September.

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 12 August 2022

Testing of the new fluoride facility is going well and this week the team has been fine-tuning the performance of the system and slowly ramping up the fluoride levels in the drinking water towards the Ministry of Health target range.

Our operators have also started receiving training on the new system. Work to optimise the facility will continue next week, which will get us closer to maintaining consistent fluoride levels.

Over the coming month we may still see variable fluoride levels (within a safe range) and the facility may need to be turned off and on to allow us to fine tune and adjust as required.

We remain on track to have the new facility fully operational in September.

 

Project progress update – Friday 5 August 2022

The container, which the new facility will be housed in, and the bulk tank, which will contain the fluoride, has been connected to the existing treatment plant, and testing is underway.

Over the month, fluoride levels will be steadily bought up to the Ministry of Health target range. During this period the fluoride facilities may also be turned on and off to allow us to fine tune and adjust as required.

We remain on track to have the new facility fully operational in September.

 

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 12 August 2022

The fluoride facility is on and operating well.

 

Project progress update – Friday 5 August 2022

The fluoride facility is on and 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 12 August 2022

We are continuing with our planning to carry out minor renewals and maintenance of the fluoride facility. This is scheduled to occur in late September.

 

Project progress update – Friday 5 August 2022

We are continuing with our planning to carry out minor renewals and maintenance of the fluoride facility.  This will now occur in September due to the impacts of COVID on our operations.

 

Previous Fluoride Dosing & Measurement at Water Treatment Plants

The percentages and monthly average that the plants achieved for the month of June 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

-

 

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.