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Manganese Discolouration Issue in Municipal Drinking Water

Posted August 16th 2023

For all the updates regarding the manganese issue, please check this page.


August 16th, 2023


For Immediate Release – August 16, 2023

RE:             Addressing the Manganese Discolouration Issue in Municipal Drinking Water


The Municipality of Callander is currently experiencing discoloured water in parts of the distribution system. This is caused by naturally-present manganese in the source water (Lake Nipissing – Callander Bay) that supplies water to the community.

Manganese is a naturally occurring mineral that is widely distributed in air, water, and soil. The manganese present in the water is causing discolouration, as it reacts to chlorine, which is part of the water treatment process.

Although unpleasant aesthetically, the temporary water discolouration does not pose a health risk. The water is tested regularly as per Ministry of Environment, Conservation and Parks (MECP) regulations and by the system operator, Ontario Clean Water Agency (OCWA). The water is in full compliance with provincial drinking water standards.

Mayor Noon says, “We are working closely with the Ontario Clean Water Agency (OCWA) and the Ministry of Environment, Conservations and Parks (MECP), who confirms that the water is safe to drink. The levels of manganese in the water are not dangerous”. He continues, “We’ve been assured that this is a common problem regionally, and throughout Ontario as natural rock formations dissolve in the water as the temperature increases, or during weather fluctuations which ‘stir up’ excess sediment. The good news is that as temperatures come down, OCWA is seeing the manganese levels starting to drop”.

What is the Municipality and OCWA Doing to Resolve this Situation?

To help with the discolouration, OCWA will be taking additional measures in the coming weeks to increase the flow of treated water through the distribution system. This will be done by initiating flushing of the distribution system two months earlier than expected. This is anticipated to begin immediately over the next few weeks. As part of this process, residents may see further discoloration, rust, or sediment in their homes, and/or laundry, fixtures/appliances. The purpose of this flushing is to decrease the amount of naturally occurring mineral deposits such as iron and manganese and reduce the amount of time the treated water sits in the system. Although flushing will not solve the issue, most residents should see an improvement in the water clarity.

How do we Prevent this from Occurring in the Future?

OCWA has been working with the Municipality to identify a treatment solution that can tackle this discoloration issue. A pilot project that has been successful in other communities is under consideration. The costs associated with the pilot will be brought forward at an upcoming Council meeting for Council’s consideration.

To reiterate, this discoloration is aesthetic – the water is safe for drinking and everyday use. Ongoing sampling and monitoring are taking place and should the situation change, residents will be notified immediately.

For more information, please contact the Municipality at 705-752-1410 or at

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