Nfld. & Labrador

The science behind manganese in drinking water

Memorial University chemistry professor Chris Kozak says it's a metal which occurs naturally, and adds manganese is needed as a micro nutrient in our diets.

We need manganese in our diets, but not too much

Memorial University chemistry professor Chris Kozak says manganese is something we need naturally in our diets. Too much, however, can cause a biological imbalance. (Jeremy Eaton/CBC)

Manganese in drinking water is a hot topic as of recent with public outcry and the city of St. John's scrambling to put together a solution to end the unwelcome mineral build up.

Memorial University chemistry professor Chris Kozak says it's a metal which occurs naturally, and adds manganese is needed as a micro nutrient in our diets. 

"In fact I had a bowl of cereal this morning, I looked at the label, it told me I got 25 per cent of my daily dose of manganese," Kozak told CBC Radio's St. John's Morning Show.

"Manganese we need biologically. It helps us form healthy bones, it helps enzymes in our bodies to process all these carbohydrates that we're getting in our breakfast cereal."

However, too much manganese can cause a biological imbalance and that's where the concern is coming from, Kozak says.

"You don't want to overdose on manganese, just like you don't want take too much of any mineral, including iron," he said.

What is manganese, anyway?

3 years ago
Duration 2:42
Memorial University chemist Chris Kozak explains all about manganese. Why is it in the water system? And why is your water dark? 2:42

"Depending on where the water is coming from, it will contain a little bit of its own manganese, but manganese is often added to water in the form of permanganate, which you can think of as a really strong bleach. And that is there to sterilize and oxidize, destroy any bacteria that are present in the water that would be cause for other concerns."

More water used in summer

The manganese found in water can become insoluble after reacting with permanganate and then "settle" out of the water, according to Kozak. It will then settle out in sedimentation tanks. 

"Sometimes, especially in the summer time where we're using an awful lot more water than normal, particularly with the hot weather we're having this July and August, there's a lot more flow of water going through the sedimentation tanks," he said. 

"And it's quite possible that this is causing some of the sedimentation to stir up and enter the actual water supply. I think this is what the city is trying to figure out, where exactly the manganese is coming from."

The real concern

While manganese levels have been rising and falling, and haven't always exceeded Health Canada's criteria for drinking water according to city reports, the real concern is how 14 per cent of city samples show roughly four times what Health Canada recommends as the maximum allowable concentration.

14 per cent of the city of St. John's water samples show roughly four times more what Health Canada recommends as the maximum allowable concentration. (Jeremey Eaton/CBC)

"Even though it's not a continuously high level, it's cause for concern. Any time you have a potential contamination in your water supply it affects many, many things," Kozak said.

"It shows how important it is to maintain our infrastructure and to monitor our infrastructure very carefully."

With files from the St. John's Morning Show

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