The Office of Drinking Water wishes to advise you of recent and upcoming Health Canada publications and public consultation processes related to iron, radionuclides, and total trihalomethanes (THM) in drinking water. These national guidelines provide important information and recommendations that may be relevant to your work and/or the operation of your water system, or your member’s or client’s systems, and we strongly recommend that you review the information included in each or share with your members or staff, as appropriate, for this purpose.             

Trihalomethanes (THMs) - Health Canada is updating its guidance on trihalomethanes (THMs) in drinking water.  The public consultation for the guideline technical document opened on January 10, 2025 and will close to new input on April 4, 2025. The existing guideline document was developed in 2006 (with an addendum in 2009), and recommended a maximum acceptable concentration (MAC) of 0.100 mg/L.  The updated guidelines propose to retain the MAC of 0.1mg/L for total THMs in drinking water.  To review and provide comments on the proposed THM guideline, please refer to Consultation: Draft Guidelines for Canadian Drinking Water Quality, Trihalomethanes - Canada.ca

Iron - Health Canada updated the iron in drinking water guidelines in December 2024.  The updated guideline now sets the aesthetic objective (AO) at 0.1 mg/L,  down from the previous level of 0.3 mg/L. Concerns about iron in drinking water are often related to consumer complaints regarding discoloured water.  The new AO aims to reduce the chances of discolored water caused by iron oxides and to improve public confidence in water quality. To review the latest changes and recommendations, please refer to the updated guideline available at:https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidelines-canadian-drinking-water-quality-guideline-technical-document-iron.html.  

Radionuclides - Health Canada is in the process of drafting a guideline for radionuclides in drinking water and is currently addressing comments received during the consultation periods which closed January 10, 2025.  The proposed guideline includes screening for gross radiation, new MACs for the most significant radionuclides in Canadian water supplies (Lead-210, Radium-226 and Radium-228), and health-based values for other radionuclides of interest including radon, tritium and isotopes of polonium, strontium, iodine, and cesium.  To review the proposed guideline, please refer to: https://www.canada.ca/en/health-canada/programs/consultation-guidelines-canadian-drinking-water-quality-radiological-parameters/document.html