Safe Drinking Water:
As has been noted,1 it can be difficult to define safe drinking water in Canada, due in part to the lack of national water quality standards. Most federal, provincial, or territorial legislation does not include a definition. The Walkerton Report writes that safe drinking water has a level of risk so small that reasonable and informed individuals would feel safe drinking it.2 It should be noted that water deemed safe does not mean that it is completely without risk. The Report notes that there is always a degree of risk involved in supplying drinking water.
In Canada, one scientific definition is that safe drinking water is free of microbiological contaminants and contains chemical contaminants at levels that do not harm human health.3 In the US, safe drinking water is defined as not containing harmful bacteria, toxic materials, or chemicals. If it meets these criteria, it is considered safe for drinking even if the water has taste, odour, colour, or mineral problems.4
For the purpose of NCCPH's Small Drinking Water System Project, safe drinking water is defined as water that is free of harmful material and contains contaminants at such low levels that the risk of drinking it is negligible.
Small Drinking Water Systems:
A review of organizations, websites, and publications has shown that there is no universal agreement upon what constitutes a small drinking water system (SDWS). Countries, municipalities, or organizations also differ in regards to what they assess in determining a small system; variables such as the number of individuals served, the number of hook-ups, the amount of time per year that the system is in use, the complexity of the system, or the amount of water distributed (flow rate) are all used. Generally, the following definitions are used on a national scale:
Canada:
- Very small drinking water systems serve less than 500 individuals
- Small drinking water systems serve fewer than 5000 individuals5
United States:
- Very small drinking water systems serve between 25 and 500 individuals
- Small drinking water systems serve between 501 and 3,300 individuals
- Medium drinking water systems serve between 3,301 and 10,000 individuals6
International:
- Very small drinking water systems serve between one and ten families
- Medium small drinking water systems serve between 50 and 500 individuals
- Large small drinking water systems serve between 500 and 4,000 individuals7
For the purpose of NCCPH's Small Drinking Water System Project, small drinking water systems are defined as serving less than 5000 individuals.
References
1. Swain H, Louttit S, Hrudey S. Report of the expert panel on safe drinking water for First Nations - Volume 1: Safe drinking water for First Nations - Government of Canada. 2006. Available from: http://www.sdw-eps.gc.ca/rprt/vlm1/archv_e.asp
2. O'Connor DR. Part 2 report of the Walkerton inquiry: A strategy for safe drinking water. Toronto: Ontario Ministry of the Attorney General; 2002. Available from: http://www.attorneygeneral.jus.gov.on.ca/english/about/pubs/walkerton/part2/
3. Commissioner of the Environment and Sustainable Development. Safety of drinking water: Federal responsibilities. Report of the Commissioner of the Environment and Sustainable Development to the House of Commons. 2005. Available from: http://dsp-psd.pwgsc.gc.ca/Collection/FA1-2-2005-4E.pdf
4. Environmental Protection Agency. Terms of environment: Glossary, abbreviations and acronyms. EPA: Communication, Education, and Public Affairs; 1997 Contract No.: EPA# 175-B-97-001. Available from: http://www.epa.gov/OCEPAterms/
5. Health Canada. Guidance for providing safe drinking water in areas of federal jurisdiction - Version 1. Ottawa: Environmental and Workplace Health; 2005. Available from: http://hc-sc.gc.ca/ewh-semt/pubs/water-eau/guidance-federal-conseils/index-eng.php
6. Environmental Protection Agency. Public drinking water systems: Facts and figures. EPA: Public Drinking Water Systems Programs; 2008. Available from: http://www.epa.gov/ogwdw/pws/factoids.html
7. International Water Association. 7th IWA Specialty Conference on Small Water and Wastewater Systems, March 7-10 2006 - Mexico City, Mexico. 2006. Available from: http://pumas.iingen.unam.mx/small2006/