Cobden Discoloured Water - August 14, 2026

The Township of Whitewater Region is aware that discoloured water continues to be experienced by residents in Cobden.  The Township began receiving reports of discoloured water on August 6th and have continued to receive several additional reports from residents each day since.  The Ontario Clean Water Agency (OCWA), the Townships water system operator, has been notified of each report received from the public and began addressing the discoloured water issue immediately by adjusting the treatment system at the Cobden Water Treatment Plant (WTP).   

When reports of discoloured water are received, OCWA will flush hydrants in the surrounding area to remove the discoloured water and follow up directly with each resident to explain the situation and provide advice on how to flush the discoloured water from their home.

It is important to understand that the manganese discolouring being observed is an aesthetic concern and is not a health concern at the levels currently present.  Nevertheless, as a precaution, residents are advised not to consume water that is visibly discoloured.

If you experience discoloured water, we encourage you to continue to contact the Township office to let us know as OCWA relies heavily on resident feedback to understand if and where discoloured water is occurring. 

Residents can report coloured water by calling the Township office at 613-646-2282, or you can submit a report through our online portal (link here: https://form.foreaction.cloud/submit/whitewater-region).  After hours reports can be submitted online or by calling the Townships after-hours reporting line at 613-647-3333.

Why is my water discoloured?

Discoloured water tends to occur in Cobden during the later summer months. This issue is typically caused by the element manganese, that is naturally present in Muskrat Lake, the source of water for the Cobden drinking water system. Weather conditions such as wind, rainfall, and temperature fluctuations, all of which have been frequent this summer, can cause mixing in the lake. This mixing results in rapid changes to manganese concentrations in the raw water, with levels sometimes fluctuating daily or even hourly.

OCWA continues to closely monitor manganese levels and adjust the treatment plant as required.  Manganese is removed through filtration following oxidation with potassium permanganate. Potassium permanganate is a highly effective oxidizing agent when applied at the correct dose. However, if the dose is too low, manganese may not be fully oxidized and removed, resulting in brown-coloured water. If the dose is too high, the excess oxidant can react with iron present in the distribution system, causing red-brown discolouration. At even higher doses, water can take on a bright pink colour. The range between underdosing and overdosing of Potassium permanganate is relatively narrow. Given the rapidly fluctuating manganese concentrations observed over the past seven to eight days, it has been challenging for operators to continuously maintain the optimal dosage.  As a result, intermittent episodes of brown water have occurred throughout the past week.  It should be noted that OCWA generally errs on the side of slightly underdosing potassium permanganate in order to avoid a pink water situation.

If you have any questions or are currently experiencing discoloured water, please do not hesitate to contact the Township.

Regards,

Deanna Nicholson

Environmental Services Superintendent