Montreal’s fluoride sunset highlights technical challenges of additive
A look inside the water department's technical arguments against fluoridation
Feb.26 2025
By David Nesseth
As Montreal squeezes the tube on its last supply of fluoride from the two remaining treatment plants that apply it, two major reports from the city’s water department are linked to the policy shift by detailing scores of logistical challenges posed by fluoridation.
They are also some of the same challenges faced by Halifax Water, a utility that struggled in secret in recent years with fluoridation, and just made its technical challenges public. Calgary, too, has faced hurdles in its bid to resume fluoridation after shelving the tooth decay prevention tool for more than a decade, mirroring the story of Windsor, Ontario.
It all starts with space. Water departments in both Halifax and Montreal have cramped chemical rooms that make it difficult to manage huge volumes of fluoride that require very particular storage, both in dry and liquid form. Then come more concerns. These include water treatment plant worker safety when handling the chemical compound, the impact of its corrosiveness on equipment, complex maintenance concerns, regulatory monitoring, dosing challenges, environmental impact, and, of course, cost.
However, many municipalities view the cost of fluoridation as being less than the potential healthcare costs of dental problems.
The reasons behind Montreal’s decision to reconsider fluoride, whether sparked by a citizen petition linked to RFK Jr.’s advocacy against fluoride in the U.S., or new studies about potential neurological impacts on children, have fueled many online searches of late. However, less attention has been given to the significant technical challenges of being one of the most fluoridated countries in the world. The experiences of Montreal and other Canadian cities shed light on these challenges, without the intention of diminishing acknowledged oral health benefits.
The City of Montreal’s water department, known as Service de l’eau, begins one of its exhaustive reports on fluoridation by setting some ground rules. Translated to English, staff noted in March 2024 that their approach to the matter is “based on technical, operational and economic considerations, from the point of view of an asset owner and operator, namely the water department; health considerations are beyond the scope of expertise of the water department’s expert.”
Water fluoridation has been practiced at the Pointe-Claire and Dorval drinking water production plants since 1955 and 1957, respectively. Montreal’s water department reports left municipal officials needing to choose between new investments in the restoration and reconstruction of infrastructure, or ending fluoridation at both plants. In the end, Montreal’s Agglomeration Council voted on November 21, 2024 to stop fluoridation, which doesn’t occur elsewhere in Quebec, apart from Saint-Georges in the Beauce region.
Notably, Laval stopped fluoridation in 2000 due to operational problems with its fluoridation equipment.
“Is it justified that only a fraction of the population of the Montreal metropolitan area has access to fluoridated water?” the water department asked in a report, noting that in the Montreal metropolitan area, just over 100,000 people receive fluoridated water, while nearly two million do not.
Space and safety
The space needed by fluoridation equipment has impacted Montreal. At the Dorval plant, the fluoridation facility was redone in 2008 to bring it into compliance with standards. Also, a building extension was built to house the equipment at a cost of some $400,000, which also allowed for the installation of a new reservoir with a daily tank and dosing system. The water department suggests that repurposing the space currently used for fluorination at the Pointe-Claire plant will improve safety and access for lime dosing equipment operations.
In the U.S., where the great fluoride debate seems ready to reach a fever pitch, the process of fluoridation has been considered so complex as to require at least one full-time fluoridation specialist for each state. Some of this is necessary to manage the risks around fluorosilicic acid systems.
In Montreal, the Dorval plant uses fluorosilicic acid, which is highly corrosive and presents potential worker safety issues in the case of a spill. Also, toxic vapours could occur through reactions with other stored products during a mishap. The water department warns that it is a particular concern due to the slope and design of the Dorval plant’s unloading area for deliveries.
“Due to the nature of the product, Dorval plant personnel are reluctant to work on the system,” states the water department report. “However, no workplace accidents or ‘near misses’ have been recorded in the last six years in connection with this process.”
The water department continues to note that indirect costs are incurred by the need to adjust the pH at the Dorval plant outlet because of the use of fluorosilicic acid.
More difficult to quantify, Montreal’s water department reports, is an increase in corrosion of equipment “on the periphery” of fluorine dosing installations. “Acid vapours can attack glass and concrete surfaces, plumbing, control devices and analyzers, requiring more frequent renewal of this equipment.”
Fluoride’s connection to corrosion, however, remains highly in question in the view of many experts, who cite a lack of direct evidence.
For the Dorval plant, a supply chain issue of fluorosilicic acid led to a total of 163 days of shutdown in 2021 – 2022, or 88% of the time for which the process was not in operation, according to the water department. The product typically needs to be transported by truck from the U.S.
The Point-Claire plant instead utilizes sodium hexafluorosilicate (Na2SiF6 in dry form) for fluoridation, often shipped from China. So, the water department also makes the case that ending these fluoridation-based shipments will further the city’s greenhouse gas reduction goals.
In Halifax, intermittent leaks have plagued the J. Douglas Kline (Pockwock Lake) water supply plant since 2021, creating safety risks around the storage and use of fluoride, the utility announced on November 29, just a week removed from Montreal’s major fluoride decision. The plant resumed fluoridation in December, after shelving the application for more than a year.
As for the Lake Major water supply plant, Halifax Water revealed that the system hasn’t had fluoride in it since 2020, when it was nearing the end of its useful life after nearly 20 years.
“The health and safety of our employees is a top priority at Halifax Water, and we are continually evaluating and mitigating risks throughout the business,” Jeff Myrick, Halifax Water’s senior manager of communications and corporate Strategy, told ES&E Magazine.
“Fluoride is considered a hazardous material even during normal operations, and the storage and handling of the product are heavily regulated. Given the safety risks presented by these operational issues, the decision was made to take it offline.”
Since 2020, plans to resume Lake Major’s fluoridation have been complicated by significant changes in lake water chemistry due to severe rainfall events. The changes required the utility to use more alum to meet regulatory standards for safe drinking water. The need for additional alum storage created a space constraint. “While alum is needed to meet regulatory requirements for water treatment, fluoride is not, and we must determine an alternative solution before it can resume,” added Myrick.
Equipment and supply costs
The City of Calgary is yet another example of fluoridation’s complex logistics and high cost. As the city looked to reintroduce fluoridation after previously abandoning it, local officials saw project costs triple in 2023. They realized they needed to spend more than $28 million on an entirely new building to house fluoridation equipment at the Bearspaw Aayer Treatment Plant. This is a significant cost, when considering that emergency repairs from the disastrous summer watermain break could cost a similar amount. Supply chain issues further delayed the project into 2024, but fluoride is expected to return to Calgary in 2025 at a cost of $1 million per year.
The City of Windsor, Ontario, has been another chapter in Canada’s fluoride history. Like Calgary, the city decided to resume the additive after previously stopping it. When the border city prepared for its return to fluoridation, it ran a study in 2021 using a pipe test loop to ensure no adverse effects to the Windsor Utilities Commission corrosion control program.
Out west, the British Columbia city of Prince Rupert is yet another example of local officials facing issues with fluoridation equipment. When the injection system failed years ago, they decided to shelve fluoridation until new funding could be secured. Earlier in 2024, the city received a federal investment of more than $77 million to fix high priority watermains and address the separation of the combined sewer system. However, fluoridation remains offline.
“Now that we have achieved substantial grant funding for system upgrades, treatment is our next objective for funding,” a Prince Rupert spokesperson told ES&E Magazine, noting that fluoridation may be next on the to-do list.
Montreal has also experienced maintenance issues with its fluoride analyzers, prompting them to switch manufacturers. They have also struggled with interference during readings and use a flow meter in addition to a continuous fluoride analyzer. “The dosing system must be accurate, calibrated and maintained with care, by personnel with the required skills,” states the water department. “The required dosing range is rather narrow.”
In addition to Montreal’s annual operating costs for fluoride, city officials peg other related fluoridation equipment refurbishments at around $19 million, as these systemst reach the end of their useful life. This cost is also on top of some $100 million in modernization projects planned for the Pointe-Claire plant and $8.2 million at Dorval.
This is all coming off of a year where the City of Montreal’s water department struggled with major watermain breaks, which will mean fast-tracking millions of more dollars for repairs. Also of note is that dosing pumps were replaced in 2012, and again in 2020 in at least one of the plants.
Focusing on water quality, not health
accessible method of preventing tooth decay.
Credit: Taweesak, stock.adobe.com
Maja Vodanovic, Montreal’s executive committee member responsible for water, told the Agglomeration Council that the upcoming water treatment plant refurbishments at the Pointe-Claire and Dorval drinking water treatment plants have complicated an already problematic issue with fluoride. She said that in addition to the $100,000 per year price tag to maintain fluoridation, plus the supply chain issues, it was a case of the technical challenges simply leading officials back to a more water quality focused position over a health one.
“We do not believe that our water filtration system should be used for other things than to provide the best quality water,” she told council. “That is already a very noble and a very complicated goal.”
Vodanovic added that maintaining the equipment to add fluoride has become unnecessarily costly and potentially wasteful. This is because it delivers fluoridated water that mostly ends up washing cars and people, fighting fires, or flushing toilets. Only an estimated one percent is used for personal consumption.
Then, the fluoride ends up in the rivers, says Vodanovic. From there, the city contends that there are still too many unknown environmental and aquatic life concerns about oxidative stress, since the city’s Jean-R.-Marcotte wastewater treatment plant does not remove fluoride.
Ultimately, officials like Vodanovic justified their decision based on the water department’s technical cautions. They framed it as a matter of consistency and uniformity in approach.
“I have to say that the city of Montreal took this decision to be coherent,” Vodanovic said in English just before the final vote passed. “We do not put fluoride in our water and we don’t intend to put fluoride in our water. We produce the water. We are competent in the matter and we want to produce the best quality water for all of Montreal.”
In its reports, the water department presents a similar position that suggests the addition of chemicals that are not necessary for drinking water but are beneficial to health, may not be its purview.
“What is clear however is that the practice of fluoridation is not essential to fulfilling the mission of the water department,” the March report states.
Health Canada maintains its support for drinking water fluoridation as a safe, universal and accessible method of preventing tooth decay. As does Dr. Mylène Drouin, Regional Director of Public Health for Montreal, who wrote to the impacted communities following the agglomeration council’s decision to note that she supports fluoridation and the evaluation of expanding fluoridation throughout the Montreal region.
Montreal’s decision reflects a growing trend of cities re-evaluating the feasibility of water fluoridation. As other municipalities face similar infrastructure challenges, the debate over fluoride’s role in public health is unlikely to end soon.
This article appeared in the February 2025 edition of ES&E Magazine.
David Nesseth can be reached at david@esemag.com
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