Manitoba’s Drinking Water Quality Standards
Manitoba’s drinking water quality standards are described in the Drinking Water Quality Standards Regulation. Chemical standards are listed in Schedule B of the regulation.
Some of Manitoba's public water systems do not meet one or more of the drinking water quality standards that came into effect in 2012 or 2017. The health risks associated with these exceedances are generally low. Water quality advisory or notices are issued where a public health risk assessment deems them appropriate. Many systems are upgrading, have already upgraded or are planning to upgrade their systems, and compliance with the standards is increasing steadily.
The most common exceedances are trihalomethanes (THMs) and haloacetic acids (HAAs). These parameters form when chlorine is added to water containing high levels of naturally-occurring organic matter. THM and HAA levels can vary widely throughout the distribution system and over the course of the year. THM levels are measured at the end of the distribution system where levels are likely to be highest. HAAs are measured at the mid-point of the distribution system where levels are likely to be highest. HAAs decrease naturally over time towards the end of the distribution system. The THM and HAA guideline values are set at a precautionary level. For more information see the THM and HAA factsheet.
Some smaller surface water systems are not fully compliant with the standards for protozoa and turbidity. The reasons for non-compliance vary but generally relate to inadequate filtration or monitoring. Higher risk systems are placed on a boil water advisory. Some systems have filters that reduce the risk but are not able to fully meet the standard for operational reasons. Others have ultraviolet (UV) disinfection that allows them to meet the protozoa standard but not the turbidity standard. For most people, there may be a low level risk of gastrointestinal illness, however, immune compromised individuals may become severely ill. For more information, see Protozoa and Turbidity fact sheets.
A small number of well water systems exceed the guideline levels due to nitrate or naturally occurring trace elements. Pregnant or nursing mothers and infants should avoid drinking water that is high in nitrate. For more information see the fact sheets on Arsenic, Fluoride, Nitrate and Uranium.
Prior to 2020, compliance with the lead standard was assessed through samples collected at the water treatment plant. When compliance is measured this way, all Manitoba public water systems meet the standard. In 2020 the standard was lowered from 0.010 mg/L to 0.005 mg/L, and the compliance point moved to the consumer's tap. Manitoba Environment and Climate Change has been working with Manitoba Health Seniors and Active Living and water system owners to develop residential tap water quality testing programs for lead in drinking water. The new tap water quality testing programs will be phased in over several years. For more information see the fact sheet on Lead.
For all of these water standards, measures can be taken to reduce exposure by water users. These measures are outlined in the fact sheets. Manitoba Environment and Climate Change is working with Manitoba Health, Seniors and Active Living and water system owners to provide information to their system users and continuously improve drinking water systems in the province.
