Draft Haloacetic Acids Drinking Guideline

Summary#

The federal government, under the Canadian Environmental Protection Act, 1999, has published a draft of the Guidelines for Canadian drinking water quality — Haloacetic acids. The proposal, from Health Canada, would set a recommended maximum concentration for a group of disinfection by-products and is open for public comment from January 9, 2026 to March 13, 2026 (comments accepted within 60 days of the notice).

What it does#

• Proposes a maximum acceptable concentration (MAC) of 0.08 mg/L (80 µg/L) for total haloacetic acids (the sum called HAA6).
  • The MAC would be calculated as a locational running annual average using at least quarterly samples from the distribution system.
• Says that if the running annual average for bromochloroacetic acid (BCAA) reaches 10 µg/L or more, water systems should take steps to reduce brominated HAA formation.
• Recommends keeping HAA levels as low as reasonably achievable (ALARA), but stresses that any steps taken must not reduce the effectiveness of disinfection.
• Describes ways to measure and reduce HAAs, including:
  • measuring the six HAA chemicals that make up HAA6;
  • removing organic material before disinfection;
  • changing disinfectant type, dose, or dosing location;
  • managing the distribution system (optimizing residuals, reducing water age, flushing, or switching to chloramines).
• Notes that iodine-containing HAAs were excluded from some analyses because they are rarely detected and data are limited.
• Clarifies this is a draft guideline (a proposal), not a new law or regulation. The draft is posted on Health Canada’s consultations page and comments may be sent by email to water-consultations-eau@hc-sc.gc.ca within 60 days.

Who's affected#

• Municipal and regional water utilities and operators, especially those that treat surface water (lakes and rivers).
• Small systems and communities where source water contains bromide, since bromide tends to increase brominated HAAs.
• Provincial and territorial drinking-water regulators and public health officials who advise or oversee local systems.
• People who drink tap water; communities with older distribution systems or long water residence times may see different HAA levels.
• If it’s unclear who will be most affected in specific places, local water suppliers or regulators can explain how HAA6 measurements relate to their systems.

Why it matters#

• Haloacetic acids are disinfection by-products that form when chlorine reacts with natural organic matter. Some evidence links them to health risks, including cancer, at higher exposures. The draft guideline aims to limit those risks by capping HAA6 at 0.08 mg/L (80 µg/L).
• At the same time, the guideline stresses not to weaken disinfection. Untreated or poorly disinfected water carries much larger health risks from microbes than the risks posed by HAAs.
• For water systems, meeting the guideline could mean changes to treatment or distribution management, which may have costs and practical implications — especially for smaller utilities.
• The proposal is now open for comment until March 13, 2026; this is the chance for utilities, experts, and the public to give feedback before the guideline is finalized.