2006-02 Changes to the BC Drinking Water Protection Act: An Analytical Laboratory's Perspective

Following much consideration by the BC Ministry of Health and at the request of numerous British Columbian Health Professionals, changes to the BC Drinking Water Protection Act (BC Reg. 352/2005 and BC Reg. 200/2003, Section 8 Water monitoring analysis) will come into effect April 1, 2006.  After this date any drinking water sample sent to a laboratory for bacterial analysis pursuant to the Drinking Water Protection Act must be analyzed for total coliform bacteria and Escherichia coli (E. coli), at minimum. This differs from the former standard which required analysis of total and fecal coliform bacteria. Fecal coliform bacteria will continue to have a Water Quality Standard in Schedule A of the Act, but will not be required to be monitored and is therefore, optional. 

Clean water has long been recognized as being critical in controlling the spread of human disease. In order to deem water as clean, or potable (drinkable), a representative water sample from the water source must be analyzed. Due to costs and time constraints, water samples are not routinely tested for every type of pathogen (disease causing substance). Instead, laboratories analyze for indicator organisms to make accurate inferences as to the water’s suitability for human consumption. An indicator organism is one whose presence in an environment indicates the presence of other contaminating substances which pose a risk to human health. Indicator organisms should ideally have the following characteristics to be considered as good indicators of human pathogens:

·         Present when pathogens are present, and absent when pathogens are absent.

·         Be present in sufficient numbers to analyze for.

·         Be consistently and exclusively associated with the source or sources of pollution and at a higher concentration than the pathogen.

·         Behave much like pathogens with respect to components of the environment, which might affect pathogen density.

·         Be easily, accurately, precisely and economically quantifiable and not subject to false positive tests.

Almost all water-associated pathogens are gastrointestinal and have been linked to human fecal contaminated water, therefore, it makes sense that the indicators of drinking water quality also be indicators of fecal contamination. To date, British Columbia drinking water purveyors have used total and fecal coliform as indicator organisms as stipulated in the BC Drinking Water Protection Act. However, there are a number of bacterial species which are included in both the total and fecal coliform assays which are not of fecal origins. Complicating matters further, Klebsiella spp. (a non-fecal indicator which reports positive in both the total and fecal assays) also multiplies in the environment. Thus, analyzing water samples for total and fecal coliform may give false positive readings. Fortunately there is another indicator organism which is more fecal specific and can be analyzed quickly, efficiently, cost effectively and according to government accredited standards: E.coli. Furthermore, E.coli is more resilient to chlorination than other pathogens excreted in human feces and is found more abundantly. Dr. P.D. Warrington of the British Columbia Ministry of Environment has concluded that “E. coli is a conservative indicator with a built-in safety factor” (Warrington, page 31).

Laboratories have at least three solid analysis options for E.coli. Acceptable and standardized methods are outlined in Standard Methods for the Examination of Water and Wastewater, 21st edition: the multiple-tube fermentation (most probable number or MPN) method, the membrane filtration (MF) method, and the enzyme substrate method. All three methods are acceptable and recognized by government accreditation bodies.

After years of re-evaluation, new epidemiological evidence, and following similar conclusions reached in many other parts of the world, the Province of British Columbia has modified its provincial drinking water guidelines. BC has recognized the limits of the fecal coliform group as an indicator for pathogens in water. Instead, the government has moved forward and chosen to focus on the fecal specific indicator and epidemiologically related E. coli, for which there are a number of cost effective, timely and accurate tests.

Warrington , P.D. Ph.D. Water Quality Criteria for Microbiological Indicators, Ministry of Environment and Parks Province of British Columbia, Victoria, B.C. March , 1988.