Info Session on Proposed Updates to Guidelines for Canadian Drinking Water Quality – Chlorite and Chlorate

Health Canada is proposing updates to the Guidelines for Canadian Drinking Water Quality for Chlorite and Chlorate. First Nations are encouraged to attend a technical information session on these proposed changes, hosted by Ontario First Nations Technical Services Corporation (OFNTSC), and to submit any comments to Health Canada.

English session: March 10th, from 1:00 to 2:00 p.m. Eastern Standard Time
French session: March 12th, from 1:00 to 2:00 p.m. Eastern Standard Time

This session will be pertinent to technical staff who support the delivery and oversight of your drinking water. Recommended participants include:

Water operators
Community-based water monitors
Public works and band managers
Engineers and technical advisors
Environmental public health officers
Circuit rider trainers

The draft guideline is available on Health Canada’s website: Draft Guideline

How to Register

To attend the English session, please register via Zoom.

How to Provide Comments

All formal comments on the proposed updates must be submitted to Health Canada by email at: water-consultations-eau@hc-sc.gc.ca. The deadline to submit comments is April 14, 2026.

Background

Health Canada works with provinces and territories, as well as other federal departments, to develop the Guidelines for Canadian Drinking Water Quality. Guidelines are periodically reviewed and updated based on new scientific information.

When a new or updated guideline is proposed, Health Canada publishes the draft technical document on its website for a 60-day public consultation period and invites written feedback. Comments are welcome on the proposed guideline, the approach used to develop it, and the potential challenges and costs of implementation.

Chlorite and chlorate are disinfection by-products of chlorine dioxide, which can be used as a disinfectant in water treatment. Chlorate can also be formed during decomposition of hypochlorite solutions (liquid chlorine, also used to disinfect water) that are stored for long periods, particularly at warm temperatures. The revised guideline technical document proposes to maintain the current Maximum Acceptable Concentrations (MACs) in drinking water of 1 mg/L for chlorite and 1 mg/L for chlorate. It would also maintain the approach for chlorine dioxide, which does not require a MAC since it quickly breaks down into chlorite and chlorate.

The session will include:

Presentation by Health Canada (30 min): Outline of the public consultation process and technical overview of the proposed updates
Q&A (30 min): Opportunity to pose questions directly to Health Canada and ISC