Canada: Ontario Proposes New Drinking Water Standards

Last Updated: February 6 2015
Article by Jennifer Kalnins Temple and Dianne Saxe

The Ontario Ministry of Environment and Climate Change (MOECC) is proposing to tighten the permissible levels of some contaminants in piped drinking water, and to adopt standards for other as yet unregulated chemicals. MOECC is holding a Regulatory Consultation until February 16, 2005. The changes will amend Ontario Regulation 169/03—Drinking Water Standards under the Safe Drinking Water Act. These standards don't apply to bottled water – another reason to drink tap water instead.

The new standards would likely require municipalities, which treat and distribute drinking water, to install new or upgraded treatment technology. Most of us (who do not own private wells) would therefore pay more for cleaner drinking water.

Ontario proposes the following new drinking water standards:

  • Lower the standard for Arsenic from 0.025 to 0.010 mg/L;
  • Lower the standard for Carbon Tetrachloride from 0.005 to 0.002 mg/L;
  • Lower the standard for Benzene from 0.005 to 0.001 mg/L;
  • Lower the standard for Vinyl Chloride from 0.002 to 0.001 mg/L;
  • New 1 mg/L standard for Chlorite;
  • "New 1 mg/L standard for Chlorate;
  • "New 0.1 mg/L standard for 2-Methyl-4-chlorophenoxyacetic acid (MCPA); and
  • "New 0.080 mg/L standard for Haloacetic Acids as an annual average of quarterly samples.

MOECC is seeking input on the following four questions:

  • Do you agree with the proposed numerical values?
  • What benefits do you see in adopting the proposed standards?
  • What are the potential impacts on municipalities and other drinking water system owners?
  • What is the desired time frame for implementation of the standards and why?

To facilitate discussion, the Ministry has posted a document on the EBR notice called "Technical Discussion Paper on Proposed Ontario Drinking Water Quality Standards" which provides an overview of the process used by the Ministry in developing the proposed standards.

For an interesting cost-benefit analysis of disinfecting drinking water, see "Cost-Benefit Analysis: Treat the Illness or Treat the Water?" by the Safe Drinking Water Foundation. The SDWF notes that the Walkerton E-Coli tragedy ultimately cost about $65 million with a burden per household of $3,764, including costs for treatment, water pickup, food replacement and travel costs, plus seven deaths. The cost to repair the offending water treatment plant (which would have prevented the tragedy) was about $10 million. Bottom line? No surprise, it's worth spending the money to properly disinfect shared drinking water.

It's not nearly as obvious that it is a good social decision to spend the money required to lower already low levels of toxics, as the MOECC now proposes. Reducing toxics has much higher costs and smaller benefits, and can create difficult tradeoffs for municipalities.

For example, disinfection is typically done by adding chlorine or other chemicals that kill bacteria. The downside of disinfection is that chlorine breaks down to smaller chemicals in drinking water that may carry some risk of cancer. Those chemicals include Haloacetic Acids (HAAs), which are covered by the Ministry's latest proposal. HAAs are a group of compounds that have not been fully studied, but some of them (e.g, dichloroacetic acid or DCA) are considered to be probable human carcinogens.

As the Ministry's Technical Paper explains (at page 15), the use of chlorine can kill or inactivate most microorganisms found in water, and the majority of drinking water systems in Canada use chlorine for that purpose. Disinfection is vital, and the risk of illness from HAAs is much lower than the risks from drinking water that has not been disinfected. The Ministry has decided that setting a maximum permissible level of HAAs in drinking water at 0.08 mg/L will sufficiently protect Ontarians without compromising disinfection. Health Canada has had an established Canadian Drinking Water Quality Guideline for HAAs at that level since 2008. The U.S. EPA's recommended level is actually set lower at 0.06 mg/L.

The MOECC's Technical Paper notes, however, that adopting the level of 0.08 mg/L for HAAs will "require an estimated 90 drinking water systems to optimize treatment processes to improve efficiency" in removing these chemicals, or to provide upgrades, or to "find other solutions." This is why municipalities must carefully review the proposed regulatory changes to consider what solutions may be required in their jurisdictions and what the costs may be.

The proposed changes for the other chemicals noted are based on the same kinds of concerns; what level of protection from cancer-causing chemicals can we technically achieve at a cost we are prepared to pay? For example, the MOECC suggests that lowering the standard for arsenic from 0.025 mg/L to 0.010 mg/L will reduce the excess lifetime cancer risk associated with drinking water containing arsenic from 80 additional cancers in a population of one million to 33 such cancers. But what else could municipalities do, to promote human flourishing, with the money that will now be spent on additional treatment? And will having to pay more for drinking water adversely affect the health of the poor in other ways? The MOECC never analyses these questions.

According to the MOECC's posting, the ministry anticipates an additional stakeholder consultation regarding the sampling, testing and reporting requirements, and the categories of drinking water systems affected as prescribed by Ontario Regulation 170/03 (Drinking Water Systems) at a future date.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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Jennifer Kalnins Temple
Dianne Saxe
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