About the Registry Search How do I ...? MyEBR FAQs Links Contact Us Home
Regulation Decision Notice:   EBR Registry Number:   012-4213
Regulatory Amendments to Update Ontario Drinking Water Quality Standards, and Testing and Reporting Requirements
Ministry of the Environment and Climate Change
Date Decision loaded to the Registry:
December 11, 2015
Date Proposal loaded to the Registry:
August 14, 2015
Keyword(s):   Drinking Water  |  Monitoring  |  Standard
Related Act(s):   Safe Drinking Water Act, 2002
Decision on Regulation:

On December 18, 2014 the Ministry of the Environment and Climate Change sought input on the “Technical Discussion Paper on Proposed Ontario Drinking Water Quality Standards” through Environmental Registry notice # 012-1594. The discussion paper proposed amendments to Ontario Regulation 169/03 (Ontario Drinking Water Quality Standards) made under the Safe Drinking Water Act, 2002 (SDWA) in order to adopt new drinking water standards for chlorate, chlorite, 2 methyl-4-chlorophenoxyacetic acid (MCPA), and haloacetic acids (HAAs), and to revise the existing standards for arsenic, benzene, carbon tetrachloride, and vinyl chloride.

On August 14, 2015, the Ministry of the Environment and Climate Change posted proposed amendments to Ontario Regulation 169/03 (Ontario Drinking Water Quality Standards) and Ontario Regulation 170/03 (Drinking Water Systems) made under the SDWA, and outlined certain changes to municipal licences that would be needed to update drinking water standards, and testing and reporting requirements.

A decision was made to proceed with the amendments to O. Reg. 169/03 and O. Reg. 170/03 consistent with the proposals as described, with minor modifications as a result of comments received during public consultation. The amended regulations were filed on December 1, 2015 and will be phased in between January 1, 2016 and January 1, 2020 as described further below include:

 a) Updating the Drinking Water Standards as per the Discussion Paper

  • The Ontario Drinking Water Quality Standards Regulation (O. Reg. 169/03) has been amended to strengthen the standards for arsenic, benzene, carbon tetrachloride and vinyl chloride and to add new standards for chlorate, chlorite, MCPA and HAAs to align with current science and best practices.

b) Updating the Sampling and Testing Requirements

  •  With respect to the four substances for which standards will be newly adopted, the following new sampling and testing requirements include:

    o Chlorite and chlorate testing will be required for systems using chlorine dioxide equipment (currently four systems in total) by amending the licences for these systems;
    o MCPA will be included in the set of organic chemicals that require testing a minimum of every one or three years (for large municipal residential systems, depending on source) or every five years (for small municipal residential systems, non-municipal year-round residential systems, and systems serving designated facilities); and
    o Municipal and private residential systems will generally need to be tested for HAAs in the distribution systems on a quarterly basis.

c) Reporting for Disinfection By-products (THMs and HAAs) and Updating Chemical Lists

  • The simplified reporting and resampling rules for disinfection by-products (THMs and HAAs) will base adverse test reporting on results from each calendar quarter and will make practices in Ontario more consistent with practices in other jurisdictions.
  • New rules will optimize the THMs and HAAs testing frequencies for small municipal systems (100 or fewer homes) and non-municipal residential systems (e.g., mobile home parks, private subdivisions) only if they have a proven history of low levels of disinfection by-products.
  • There are thirteen ‘legacy’ pesticides which are no longer in commercial use, have been de-listed from the federal guidelines, and have not been detected in drinking water samples for at least ten years. Based on this, these thirteen chemicals have been removed from the regulations.

d) Providing Phase-In Periods for the Amendments to Take Effect

To allow system owners/operators a period to collect baseline information and provide for any necessary system upgrades the amendments will be phased in as follows:

  • New sampling, testing, reporting, and resampling requirements - will come into effect as of January 1, 2016;
  • New testing requirements for HAAs - will come into effect as of January 1, 2017;
  • Updates to standards for carbon tetrachloride, benzene, vinyl chloride, chlorate, chlorite, and MCPA - will come into effect/require reporting as of January 1, 2017;
  • Updates to standard for arsenic - will come into effect/require reporting as of January 1, 2018; and
  • New standard for HAAs and HAAs testing optimization rule for smaller systems - will come into effect/require reporting as of January 1, 2020.

Comment(s) Received on the Proposal:   10

Public Consultation on the proposal for this decision was provided for 45 Days, from August 14, 2015 to September 28, 2015.

As a result of public consultation on the proposal, the Ministry received a total of 10 comments: 7 comments were received in writing and 3 were received online.

Additionally, a copy of all comments are available for public viewing by contacting the Contact person listed in this notice.

A selection of these comments are available:

Effect(s) of Consultation on this Decision:

Input on this proposal was gathered through two postings on the Environmental Registry, a posting on the Regulatory Registry, and targeted consultation with key stakeholders, including the Ontario Drinking Water Advisory Council (ODWAC), Ontario Water Works Association, the Ontario Municipal Water Association, and local Medical Officers of Health.

Environmental Registry Notice 012-1594 (posted December 2014)

On December 18, 2014, the ministry sought input on a technical discussion paper through an EBR posting for a 60-day comment period. The paper summarized health-related information associated with each of the substances discussed and included some questions regarding impacts of the proposed updates.

In response to the posting of the discussion paper, the ministry received 26 comments from a broad range of stakeholders that included large and small municipalities, municipal associations, laboratory associations, public health units/associations, non-governmental organizations (NGOs), and individuals.

Comments received were generally supportive of the ministry strengthening Ontario’s drinking water standards and recognized the human health benefits. Some concerns were expressed about potential cost impacts and implementation time frames, the need for stringent requirements on specific substances e.g., tritium and the need for more detailed information on specific testing requirements.

Based on the comments received, a more detailed regulatory proposal was developed to include testing requirements, phase-in dates and provisions.

Environmental Registry Notice (012-4213) and Regulatory Registry Posting – August 2015:

The ministry posted a more detailed regulatory proposal, including draft amending regulations, on the Environmental and Regulatory Registries on August 14, 2015 for a 45-day comment period.

The ministry received a total of ten comments from municipalities, utilities, a water agency, industry associations, a company manufacturing water treatment equipment, a non-governmental organization, a small system owner/operator, and unidentified stakeholders.

Comments received expressed support for the implementation time frames and sampling changes and are reflected in the final Regulation. Additional comments on language and clarity were also added to the Regulation.


Satish Deshpande
Team Leader
Ministry of the Environment and Climate Change
Environmental Sciences and Standards Division
Standards Development Branch
Drinking Water Standards
40 St. Clair Avenue West
7th Floor
Toronto Ontario
M4V 1M2
Phone: (416) 327-4689

Additional Information:

The following government offices have additional information regarding this Decision. To arrange a viewing of these documents please call the Ministry Contact or the Office listed below.

Drinking Water Management Division
135 St. Clair Avenue West
Floor 14
Toronto Ontario
M4V 1P5
Phone: (416) 314-4475

The documents linked below are provided for information purposes only
All links will open in a new window