Canada Gazette, Part I, Volume 160, Number 2: GOVERNMENT NOTICES
January 10, 2026
DEPARTMENT OF HEALTH
CANADIAN ENVIRONMENTAL PROTECTION ACT, 1999
Guidelines for Canadian drinking water quality — Haloacetic acids
Pursuant to subsection 55(3) of the Canadian Environmental Protection Act, 1999, the Minister of Health hereby gives notice of the draft Guidelines for Canadian drinking water quality — Haloacetic acids. The proposed guideline document is available from January 9, 2026, to March 13, 2026, and can be found on Health Canada’s Environment and workplace health consultations web page. Any person may file written comments on the proposed document with the Minister of Health within 60 days after publication of this notice. Comments must be sent by email to water-consultations-eau@hc-sc.gc.ca.
January 9, 2026
Greg Carreau
Director General
Safe Environments Directorate
On behalf of the Minister of Health
ANNEX
Proposed guideline
A maximum acceptable concentration (MAC) of 0.08 mg/L (80 µg/L) is proposed for total haloacetic acids (HAA6) in drinking water. The MAC is based on a locational running annual average of a minimum of quarterly samples taken in the distribution system. If the locational running annual average for bromochloroacetic acid (BCAA) is measured at a concentration equal to or greater than 10 µg/L, steps should be taken to reduce brominated-HAA formation.
Water treatment systems should make every effort to maintain concentrations as low as reasonably achievable (ALARA) without compromising the effectiveness of disinfection.
Given the potential health effects of HAAs, and the limited information on the risks and uncertainties of other chlorinated, brominated and iodinated disinfection by-products, it is recommended that treatment plants strive to maintain HAA levels ALARA. It is important to note that the health risks from disinfection by-products, including trihalomethanes, are much less than the risks from consuming water that has not been disinfected. Therefore, efforts to manage HAA levels in drinking water must not compromise the effectiveness of water disinfection.
Exposure
Haloacetic acids (HAAs) are a group of compounds that can form when the chlorine used to disinfect drinking water reacts with naturally occurring organic matter in water such as decaying leaves and vegetation. The use of chlorine in the treatment of drinking water has virtually eliminated waterborne diseases, since chlorine can kill or inactivate most microorganisms commonly found in water. Most drinking water treatment plants in Canada use some form of chlorine to disinfect drinking water. Disinfection is an essential component of public drinking water treatment; the health risks from disinfection by-products (DBPs), including HAAs, are much less than the risks from consuming water that has not been adequately disinfected.
Health Canada identified 13 different types of HAAs that could be found in disinfected drinking water. These include 9 chlorine and bromine-containing HAAs and 4 iodine-containing HAAs. The specific HAAs targeted by the current Canadian drinking water quality guidelines are monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), monobromoacetic acid (MBAA), and dibromoacetic acid (DBAA). This document proposes to include BCAA in addition to these five HAAs; the sum of these is referred to as HAA6.
Levels of HAA concentrations are generally higher in treated surface water than in treated groundwater because of the high organic content in lakes and rivers. Levels of HAAs are expected to be higher in warmer months because of the higher concentrations of organic precursor materials in the raw water and because the rate of formation of DBPs increases at higher temperatures. The presence of brominated HAAs will also depend on the presence of bromide in the source water.
The ingestion of HAAs in drinking water is the main source of human exposure to HAAs. Dermal and inhalation exposure of HAAs is not expected to contribute significantly to overall exposure.
Health effects
HAAs are a large group of chemicals; some have more scientific data available than others. To better understand the risk from the group of HAAs, Health Canada analyzed the health information for all 13 HAAs as a mixture. Carcinogenicity (the ability to produce tumours) is reported at low concentrations of HAAs. The mixture analysis considered how HAAs may act on the body to lead to the development of carcinogenicity. Since iodine-containing HAAs had limited human health effect data and they had very low detection rates and concentrations in Canadian water, they were excluded from the subgroupings.
Chlorinated HAAs are found at the highest levels in drinking water. While brominated HAAs are less prevalent than chlorinated HAAs, they are more potent and have the potential to cause health effects at lower concentrations. For this reason, measurements of BCAA (the most common brominated HAA in Canadian waters that has health effect data) should be used as an indicator of locations with elevated concentrations of brominated HAAs. The proposed HAA6 guideline is considered to be protective of health for all HAAs, considering the proportion of chlorinated and brominated HAAs seen in Canadian drinking water.
Analytical and treatment considerations
The development of a drinking water guideline takes into consideration the ability to both measure the contaminant and remove it from drinking water supplies. Several standardized analytical methods are available for measuring HAAs in water concentrations well below the proposed MAC and individual BCAA concentrations well below 0.01 mg/L (10 µg/L). Measurements for total HAA6 in a water sample should include MCAA, MBAA, DCAA, DBAA, TCAA and BCAA.
The approach to reduce exposure to HAAs is generally focused on minimizing the formation of HAAs using strategies such as organic precursor removal prior to disinfection and changing disinfectant type or dose and the dosing location. This should include assessing the presence of bromide in the source water and characterization of brominated HAA species. It is critical that any method used to control levels of HAAs must not compromise the effectiveness of disinfection.
Distribution system
HAAs continue to form within the distribution system. For this reason, it is recommended that water treatment systems develop a distribution system management plan to minimize the formation of HAAs. Strategies to reduce HAA formation may include optimizing chlorine residuals, switching to chloramines, decreasing water age, and system flushing. Well-developed, calibrated and maintained distribution system models may provide another option to assess water age and simulate chlorine decay and HAA formation. Any control strategy should not compromise the effectiveness of disinfection.
PRIVY COUNCIL OFFICE
Appointment opportunities
We know that our country is stronger — and our government more effective — when decision-makers reflect Canada’s diversity. The Government of Canada has implemented an appointment process that is transparent and merit-based, strives for gender parity, and ensures that Indigenous peoples and minority groups are properly represented in positions of leadership. We continue to search for Canadians who reflect the values that we all embrace: inclusion, honesty, fiscal prudence, and generosity of spirit. Together, we will build a government as diverse as Canada.
We are equally committed to providing a healthy workplace that supports one’s dignity, self-esteem and the ability to work to one’s full potential. With this in mind, all appointees will be expected to take steps to promote and maintain a healthy, respectful and harassment-free work environment.
The Government of Canada is currently seeking applications from diverse and talented Canadians from across the country who are interested in the following positions.
Current opportunities
The following opportunities for appointments to Governor in Council positions are currently open for applications. Every opportunity is open for a minimum of two weeks from the date of posting on the Governor in Council appointments website.
| Position | Organization | Closing date |
|---|---|---|
| Parliamentary Budget Officer | Office of the Parliamentary Budget Officer |