Effect of water distribution system on drinking water quality in First Nations communities in Manitoba, Canada
Bibliographic record
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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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".