Fluoridation of Calgary's water supply delayed again

After voting in favour of resuming water fluoridation in 2021, Calgarians are still waiting for that to happen, and now the city says they will have to wait a little longer.

While it has finished installing the necessary equipment to resume adding fluoride to drinking water at both the Glenmore and Bearspaw treatment plants, the city needs more time to complete the shift, according to an update released Thursday.

"After undertaking the initial commissioning steps, we determined it will require additional time to allow us to ensure all equipment and systems are checked, inspected and tested to ensure they are all performing as designed," the city's statement reads.

The resumption of fluoridation is now expected to occur later in the second quarter of this year.

Once a date is confirmed, the city says it will provide an update four weeks in advance.

The city's plan to resume fluoridation of its water supply dates back to a plebiscite in the 2021 municipal election followed by a council vote in November 2021.

While the system was initially anticipated to be in service by September 2024, the city said it was delayed until this year due to resource challenges and uncertainty with the global supply chain.

Calgarians first voted in favour of fluoridation in 1990, following several failed votes between 1957 and 1971.

In 2011, the city stopped adding fluoride to its water.

Infrastructure upgrades were needed at Calgary's two water treatment plants to bring fluoridation back, after the city's previous infrastructure for this purpose reached the end of its lifecycle. It was decommissioned and removed following council's decision to stop fluoridation in 2011.

Cities that add fluoride to their water typically aim for a level of 0.7 milligrams per litre in order to improve dental health among the populations they serve.

Regular testing of Calgary's treated water in 2014 found naturally occurring fluoride levels of between 0.08 and 0.26 milligrams per litre.

The naturally occurring fluoride originates from erosion of rock and soil in the watersheds that supply the city. Natural fluoride levels tend to be slightly higher in water from the Elbow River as compared to the Bow River, and usually the concentrations are highest in the winter.

Naturally occurring levels as high as 0.4 milligrams per litre have been observed in city tests since fluoridation was stopped in 2011.