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Safe Drinking Water Act: The Ontario Ministry of the Environment and Climate Change is still accepting public comments on proposed changes to Ontario Drinking Water Quality Standards, and Testing and Reporting Requirements for drinking water systems and municipal licences. The proposed changes will increase monitoring and water treatment costs for some drinking water systems, in order to make drinking water safer. The changes will be phased in, and are partly offset by relaxing some monitoring requirements that have proven unneeded.

The main changes are:

“1a) Implementing Proposed Ontario Drinking Water Quality Standards

As described in the discussion paper, Schedule 2 to Ontario Regulation 169/03 is proposed for amendment as follows:

  • Strengthen the standards for four substances already listed:
    o arsenic (from 0.025mg/L to 0.010 mg/L);
    o carbon tetrachloride (from 0.005mg/L to 0.002 mg/L);
    o benzene (from 0.005mg/L to 0.001 mg/L);
    o vinyl chloride (from 0.002 mg/L to 0.001 mg/L); and,
  • Adopt standards for four substances not currently listed:
    o chlorate (1 mg/L);
    o chlorite (1 mg/L);
    o 2-methyl-4-chlorophenoxyacetic acid [MCPA] (0.1 mg/L); and,
    o haloacetic acids [HAAs]  (0.080 mg/L as a running annual average of quarterly results).

1b) Updating the Sampling and Testing Requirements

With respect to the four substances for which standards would be strengthened (i.e. arsenic, carbon tetrachloride, benzene and vinyl chloride), the existing sampling and testing requirements in Ontario Regulation 170/03 would continue to apply.

With respect to the four substances for which standards would be newly adopted, the following sampling and testing requirements are proposed:

  • Chlorate (new standard of 1.0 mg/L) testing would only be required for municipal drinking water systems using chlorine dioxide treatment equipment (currently 4systems in total). Testing requirements would be prescribed within the municipal licences for these systems, which would be updated as needed. Ontario Regulation 170/03 would not be amended to include testing requirements for chlorate;
  • Chlorite (new standard of 1.0 mg/L) testing would also only be required for municipal drinking water systems using chlorine dioxide treatment equipment. As with chlorate, testing requirements for chlorite would be prescribed within the municipal licences for these systems and Ontario Regulation 170/03 would not be amended;
  • MCPA (new standard of 0.1 mg/L) would be added to the list of organic chemicals that require testing a minimum of every 1 or 3 years (for large municipal residential systems, depending on source) or a minimum of every 5 years (for small municipal residential systems, non-municipal year-round residential systems, and systems serving designated facilities); and
  • HAAs (new standard of 0.80 mg/L expressed as a running annual average of quarterly results) would need to be tested on a quarterly basis by municipal and non-municipal year-round residential systems providing chlorination or chloramination at a location in the distribution system that is likely to have an elevated potential for the formation of HAAs (similar to current requirements for THMs).”

Comments on EBR Registry Number: 012-4213 may be filed until September 28.

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