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Tavares Group Blog

Changes to Ontario’s Drinking Water Legislation

By: Kirsi McLandress, M.E.S, EMS-LA, Sustainability Associate, Tavares Group Consulting Inc.
February 2016

As featured in our recent newsletter, December 2015 was a big month for those involved in municipal drinking water systems in Ontario, with amendments to regulations and proposed changes to the DWQMS being announced.  With the recent lead issue in Flint Michigan making national headlines in Canada and the 16 year anniversary of the Walkerton Water Crisis here in Ontario this May, we are continually reminded of the importance of water regulations, and their role in providing clean drinking water to residents.

After two proposal postings on the EBR, the Ministry of Environment and Climate Change proceeded with amendments to O.Reg. 169/03 Ontario Drinking Water Quality Standards and 170/03 Drinking Water Systems. The significant amendments include:

i. Updating O. Reg. 169/03 to strengthen the standards to arsenic, benzene, carbon tetrachloride and vinyl chloride. New standards which align with current science and best practices have been added for chlorate, chlorite, MCPA and HAAs

SubstanceOutdated RequirementAmended Requirement
Arsenic0.025 mg/L0.010 mg/L
Carbon tetrachloride 0.005 mg/L0.002 mg/L
Benzene0.005 mg/L0.001 mg/L
Vinyl Chloride0.002 mg/L0.001 mg/L
Chlorite-1 mg/L
Chlorate-1 mg/L
MCPA-1 mg/L
HAAs-0.080mg/L

ii. Sampling and Testing Requirements for the newly added substances have been identified:

  • Systems using chlorine dioxide equipment will be required to complete chlorite and chlorate testing.
  • MCPA is to be included in the set of organic chemicals that require testing every one or three years (depends on source) or every five year (small municipal residential systems, non-municipal year-round residential systems, and systems servign designated facilities); and
  • Quarterly HAA testing in the distribution systems of municipal and private residential system.

iii. Reporting and re-sampling standards for THMs and HAAs (disinfection by-products) will base adverse test reporting on results from each calendar quarter. Additionally, testing frequencies will be optimized for small municipal systems and non-municipal systems with a history of low levels of disinfection by-products.

iv. Finally, thirteen pesticides which have not been detected within drinking water systems for ten years have been removed from the regulations.

The aforementioned amendments will be phased in over the next four years to allow system owners and/or operators the opportunity to collect baseline information and complete required system upgrades. Currently, the new sampling, testing, reporting and re-sampling requirements came into effect January 1, 2016.  Subsequent phase-in dates are:

  • January 1, 2017: Testing requirements for HAAs and updates to standards for carbon tetrachloride, benzene, vinyl chloride, chlorite, and MCPA come into effect/ require reporting
  • January 1, 2018: Updates to standards for arsenic come into effect / require reporting
  • January 1, 2020: New standards for HAAs and HAAs testing optimization rule for smaller systems will come into effect / require reporting.

Make sure to check out our next blog in this series detailing the proposed changes to the Drinking Water Quality Management System. As always, our team of certified DWQMS auditors is here to help, contact us!