Manganese levels remain high in Casselman, Ont. drinking water

The municipality of Casselman has issued a water quality advisory due to high levels of manganese in the drinking water.

The Eastern Ontario Health Unit says the levels of manganese "dropped significantly" earlier this week, but the levels in the tap water remain higher than the Health Canada guidelines.

Earlier this month, residents raised concerns about drinking water that is dark, appearing dirty or the colour of apple juice. The discoloured water is because of high levels of manganese – a mineral distributed in air, water and soil – present in the South Nation River, according to the municipality.

In an update this week, the municipality said it has issued a water quality advisory for the Municipal Water Distribution System due to manganese levels above the Canadian Drinking Water Quality guidelines, and the advisory will remain in effect for further notice.

"Boiling the water will not lower the manganese level," the municipality said. "Showering and bathing with this water is safe."

The Eastern Ontario Health Unit recommends people use bottled water or another source of water for preparing baby formula for infants and food or drinks for young people.

According to Health Canada, the maximum acceptable concentration (MAC) for total manganese in drinking water is 0.12 mg/L (120 µg/L). The aesthetic objective (AO)--that is, the amount that affects how the water looks, smells and tastes--for total manganese in drinking water is 0.02 mg/L (20 µg/L). 

The Eastern Ontario Health Unit says there has only been one day in the past month where the level of manganese exceeded the 1 mg/L – on July 17.

In a statement, the health unit says the manganese levels dropped significantly to 0.24 and 0.105 mg/L on July 18 and 19.

"Given that the water meets all Ontario drinking water standards, it remains safe for adults and older children to consume despite the discolouration," the health unit said.

"The EOHU is monitoring the situation on a daily basis. Should the levels reach and remain higher than 1 mg/L for more than 10 days, at that point the EOHU will recommend an alternate drinking water source for everyone."