Health information related to discoloured drinking water in the City of Winnipeg
Winnipeg Health Region
Published Friday, July 17, 2015
Discoloured drinking water has been flowing out of some Winnipeg taps again. While the City continues to address the problem, the issue has raised questions about potential health risks related to levels of manganese and iron in the discoloured water. The following fact sheet has been prepared by the Winnipeg Health Region to provide some basic information on discoloured water and health:
What causes discoloured water?
Discoloured drinking water can occur in any part of the City of Winnipeg. The discoloration can be caused by sediments in the water distribution pipes, including minerals such as manganese and iron. Both manganese and iron are known to affect the colour and taste of water, and may stain plumbing fixtures or laundry.
What are manganese and iron?
Manganese and iron are naturally-occurring elements found in the soil and water. Both iron and manganese are essential nutrients for humans and animals, with humans getting most of these nutrients from food.
Manganese is found in many healthy foods, including nuts, beans, fruits and leafy green vegetables. Food contributes approximately 100 to 1,000 times more total manganese to our daily intake than drinking water does.
Iron is found in many foods and supplements. Iron in our drinking water may affect the taste and color of the water, but is not easily absorbed into the body.
Are there standards which govern the allowable levels of manganese and iron in drinking water?
Provincial standards for drinking water are based on the Guidelines for Canadian Drinking Water Quality. Provincial standards focus on health. There are no national health-based guidelines for either iron or manganese at present, so currently there are no provincial standards.
The Guidelines for Canadian Drinking Water Quality do include aesthetic objectives for both iron and manganese. Aesthetic objectives are targets intended to minimize problems with the colour, taste or smell of the water. The Guidelines for Canadian Drinking Water set an aesthetic objective for manganese of 0.05 mg/L and for iron of 0.3 mg/L.
Health Canada is currently in the process of reviewing the available evidence for health effects associated with manganese in drinking water. Early indications suggest that a health based guideline for manganese will be developed. The World Health Organization (WHO) has set a health-based guideline level of 0.4mg/L based on average lifetime consumption.
Are there health concerns about manganese in our drinking water?
There are few studies available on the risks from exposure to manganese from drinking water. In some studies, high levels of manganese in drinking water were associated with possible neurologic effects. New studies have become available recently, and these are being reviewed by Health Canada as part of the guideline development process.
The average manganese level in Winnipeg drinking water has remained below the aesthetic objective for manganese (0.05mg/L), and is far below the World Health Organization's health-based guideline level of 0.4mg/L for daily use. Levels of manganese in the discolored water are typically higher than the aesthetic objective, but lower than the WHO guideline.
Are there health concerns about iron in our drinking water?
Although ingesting large quantities of iron in any form (ex: supplements) can be harmful, the concentrations of iron identified in Winnipeg's drinking water (discoloured or otherwise) would not be expected to cause any health effects in the short or long term.
Is discoloured water safe to drink?
Residents are advised not to drink discoloured water or use it for purposes such as preparing food, beverages or infant formula; however, drinking small amounts of discoloured water should not pose a health threat if accidentally consumed. City of Winnipeg water is subject to extensive water quality monitoring, and none of the information collected to date indicates there are any bacteria or viruses in discolored water that could result in illness.
Occurrences of discoloured water should be reported to the City of Winnipeg's 311 service. Reporting the concern to 311 helps the city track discoloured water events, which helps identify the cause and address the problem. The City provides instructions about running the water until it is clear before drinking it.
For further information: