Effect of water distribution system on drinking water quality in First Nations communities in Manitoba, Canada
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Date
2022-01
Authors
Eragoda Arachchilage, Geethani
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Abstract
Approximately 50% of the homes on First Nation reserves in Manitoba, Canada, receive piped water from water treatment plants (WTP). Of the remaining homes, 31% are equipped with cisterns filled by a water truck. The overall objective of this thesis research was to compare the quality of tap water in homes with piped water versus those with cisterns. The study was in collaboration with three First Nations communities in Manitoba. Each community was predominantly equipped with belowground concrete cisterns, belowground fibreglass cisterns, or aboveground polyethylene cisterns stored in insulated shelters. Free residual chlorine concentration was significantly lower in water samples from homes with cisterns than piped water. The frequency and severity of Escherichia coli and total coliform contamination were significantly greater in drinking water from belowground concrete and fibreglass cisterns than in piped water samples in each community. The contamination of belowground cisterns by coliform bacteria was greatest in late spring. Data obtained under the Access to Information Act for 2014 and 2018 showed no clear evidence of improved water quality in any of the Tribal Councils linked to the three communities. Field and laboratory chlorine disappearance studies indicated a greater contribution of concrete cistern walls than bulk water to the disappearance, hence lowering free residual chlorine concentration in belowground cisterns. Treated water from the WTP in two of the First Nations communities frequently exceeded the Health Canada guideline of 100 µg L-1 total trihalomethanes (TTHMs), as did 75% of piped water samples and 70% of cistern water samples. Although the water distribution system had no significant effect on TTHM concentration, sampling month significantly affected due to temporal changes in source water dissolved organic carbon content. Dissolved organic carbon removal before further water treatment might be an important process in effectively reducing TTHMs formation, and thereby decreasing the exposure of residents to high levels of TTHMs. Additional treatment at household level, regular cleaning, and maintenance of belowground concrete and fibreglass cisterns are important to reduce the risk of water-borne illnesses. Also, belowground cisterns must be replaced with aboveground cisterns to reduce coliform contamination, although piped water is the preferred option.
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Keywords
Drinking water, Cisterns, Piped water, Chlorine, Escherichia coli, Total trihalomethanes, Chlorine decay
Citation
Amarawansha, G. E. A., Zvomuya, F., & Farenhorst, A. (2021). Water delivery system effects on coliform bacteria in tap water in First Nations reserves in Manitoba, Canada. Environmental Monitoring and Assessment, 193(6), 1-16.