Drinking Water Supply and Management Practices in British Columbia, 1997-98

Article excerpt


Background: Questions regarding control over a water fluoridation system in a British Columbia (BC) community led to a drinking water management survey in 1997-98.

Method: A questionnaire was constructed based on published drinking water control and management criteria and was sent to 91 communities.

Results: 73/91 surveys were returned (80% response rate); 31 reported a protected water supply system, 40 reported logging and/or cattle grazing in watershed areas, 25 reported a lack of primary disinfection. Water fluoridation was reported in 12 locations, 3 of which did not monitor fluoride levels. Testing for protozoans was done routinely in 19 locations, 15 using approved laboratories. 15 water contamination events were reported, 9 of biological origin. Statistically significant associations were found between contamination events and: wooden delivery systems, lack of primary chlorination, increased number of protozoan tests, and increased number of personnel.

Interpretation: At the time of the survey in British Columbia, a number of communities were vulnerable to preventable drinking water contamination.

During a 1987 investigation of several Down's syndrome births, all registered within a couple of months in a small British Columbia (BC) community,1 a number of issues became apparent. As some of these births occurred in families living a few blocks from one another and serviced by the same local water supply substation, this water supply was investigated. During investigations of this nature, one often encounters anomalies that are not necessarily related to the problem that initiated the research. In this case, it was observed that the water supply was fluoridated and the person looking after this process was a local municipal employee. This employee would take a "bucket" from "this container" and add it to a reservoir on the self-metering fluoridation system. There was no apparent display of knowledge by the employee regarding the critical concentrations and the potential toxic effects of the material that he added to the water system. The monthly fluoride concentrations recorded by the Ministry of Health, based on weekly water sample analyses, indicated levels at, or below, the 1 ppm therapeutic dose.2 Upon further questioning, it became apparent that these levels were based on the concentration in pooled samples, composed from weekly samples that had accumulated. Subsequent analyses of individual daily samples indicated wide fluctuations in water fluoride levels. These observations led us to investigate in 1997-98 the type of drinking water management practices that were in use in British Columbia.


A questionnaire was constructed based on recommended drinking water treatment, distribution, control, and maintenance practices, which are available and have been described in numerous publications.3-6 The questionnaire was tested with a local water purveyor, and corrected prior to being mailed to the water purveyors of 91 communities in BC. A self-addressed return envelope was included. Follow-up telephone calls were made to remind individuals to complete and return the questionnaires.


Of the 91 questionnaires sent out, 73 were returned (80% response rate). The questionnaire included a question regarding the position held by the individual who was providing the details, and it was found that in 62/73 locations, the questionnaires had been filled out by individuals who held supervisory positions.

The collective information that was obtained from the questionnaires has been summarized in Table I. Some of the main findings were that, out of the 73 locations, only 36 had a protected water supply system, 5 of which were only partially protected. A total of 40 locations reported logging and/or cattle grazing in the watershed areas. Some kind of water filtration was present in 23 locations. Primary disinfection using chlorine was present in 48 locations, and 1 location used ozone. …