Exploring Potability in Water
Regarding water, potability is a term used in multiple different contexts with varying perceptions of its true meaning. Generally it's referenced when evaluating a water source in rural areas where no municipal water treatment services are available. 

In this article, the term potability and its use in different contexts is explored, as well as generalizations of the public perceptions when describing water quality. Generally the term potability is used to imply that a water source is safe to drink and use unless otherwise stated.

Glass containing water contaminationGeneral Definition 
The technical definition of potable water is: Water that is suitable for human consumption. This definition implies that the water is drinkable as well as "safe", in reality drinkable water is free of unpleasant odours, tastes and colours, and is within reasonable limits of temperature. Safe water contains no toxins, carcinogens, pathogenic microorganisms, or other health hazards. 

Health Canada Definition 
Potable water is defined as water that is safe to drink. Water is considered safe to drink when it meets the guidelines set out in Health Canada's document Guidelines for Canadians Drinking Water Quality – Summary Table. This includes microbiological, chemical, physical, and radiological parameters. 

Municipal Definition 
Potable water, also known as "drinking water", comes from surface and ground sources. It's treated to levels that meet provincial and federal standards for consumption. The water from natural sources is treated for microorganisms, bacteria, toxic chemicals, viruses, and faecal matter. 

Real Estate Definition 
In rural areas, a bacterial water sample produces a certificate of potability from a jurisdictional authority. This indicates that there is no significant evidence of bacterial contamination. 

Public Health Ontario 
“Your well water can affect the health of everyone who consumes it. At PHO, we test for the indicators of bacterial contamination”, specifically e.Coli and Coliform bacteria. We do not test for other contaminants such as chemicals. This means that even if your results show there is no bacterial contamination in your drinking water, it still may be unsafe to drink.”1

Jeff Wahl CommentPersonal Experiences
Frequently there has been involvement with a multitude of individuals who believe that a standard public health unit sample with favourable results is evidence of potable water that is safe for consumption. This is thought despite it being a report on only two microbiological parameters; with no testing for chemical, physical, and radiological parameters set out in the Canadian Drinking Water Quality Guidelines.

The term “potable” can have many different definitions depending on the jurisdiction which is governing the quality of water. Public perception of water when it is deemed potable, is generally that it is safe to use and consume. Jurisdictions do not claim that water is free from all contaminants when classified as potable. Public perceptions are commonly in line with the particular jurisdiction which regulates the water for specific contaminants with varying degrees of understanding about the overall water quality.

The Definition of Potability is Subject to Broad Interpretation

CanadaCanadian Drinking Water Quality Guidelines (CDWQG) Consideration

Total Coliform and e.Coli are the only two parameters tested for in a Health Unit water sample in Ontario. Their presence can cause illness with severe cases resulting in fatalities. 

The CDWQG contains 97 parameters with minimum safety levels of which e-Coli and Total Coliform are only two. The remaining 95 parameters are not part of a standard Health Unit water test. 

Some of these parameters include Arsenic, Mercury, Nitrate, Copper, Per- and poly-fluoroalkyl substances (PFAS), Trihalomethanes, Lead, Sodium, Chemicals, Microplastics, Pharmaceuticals, Pesticides, Glyphosate and numerous other contaminants deemed worthy of governing by the CDWQG.  

         Water Should be Safe to Use & Consume

Best Practice Recommendation
Understanding the term “Potability” is important to decide what type of water is suitable for drinking in your home, cottage, or business. If you are unsure about your water source, consult a certified water treatment professional who can provide you with guidance, recommendations, and best practices for proper water treatment.

Volume 7 – Issue 3 Wahl H2O - Water Awareness
Copyright 2024 Jeff Wahl – Wahl Water | All Rights Reserved
  Contact Jeff via email [email protected]

1 https://www.publichealthontario.ca/en/Laboratory-Services/Well-Water-Testing

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