A study that found high fecal bacteria counts and antibiotic resistance genes in water samples taken from about 30 locations in a fly-in Northern Manitoba community demonstrates that simply having a properly functioning water treatment plant does not ensure that the water coming out of taps is safe to drink.
The study, which was published in the American Society for Microbiology’s Applied and Environmental Microbiology journal in May, indicates that something within the distribution system is contaminating the water from the treatment plant or quenching the chlorine it contains, says Dr. Ayush Kumar, an associate professor in the University of Manitoba’s Department of Microbiology, one of its authors.
“It appears that as soon as the water gets into the distribution system there is contamination,” Kumar says. “Water tested at the treatment plant, post treated water, there were no bacteria and chlorine levels were as desired. Even if we went into tap water from households, chlorine levels went down and that would explain, at least partially, why bacteria numbers went up. For some reason chlorine concentration is going down, again we don’t know why, but that seems to be a correlation. There could be something in the pipes maybe that is actually quenching chlorine. Chlorine tends to be unstable so a little bit of concentration going down is expected but not to the extent that we saw.”
The findings of the study, which is based on samples collected in June 2014, were surprising to the microbiologists who conducted it, revealing coliform counts as high as 10,000 parts per 100 millilitres, far exceeding the Health Canada guidelines of no fecal bacteria.
“I think we expected some bacteria in the water samples just based on what we have seen for a number of other communities across Canada,” said Kumar. “Only some houses have access to piped water so what we were expecting was that maybe households that do not have piped or running water, there might be a bit of a problem there. The extent that we found was certainly not expected. The fact that we found these bacteria in piped water was not expected at all.”
And while the bacteria strain of e. coli they detected is not harmful to people - it is present in humans’ gastrointestinal tracts - its presence means that other bacteria that could cause illness are likely present as well.
“I may be having a gastrointestinal tract infection which means that I’m releasing some of those pathogens in there as well,” Kumar says. “Even though we tested for e. coli what this suggests is potentially you can have disease-causing bacteria in the water sample. Water is one of the most common vectors for gastrointestinal infections so drinking contaminated water puts us at very high risk of getting gastrointestinal infection because somebody who has those infections is obviously releasing a lot of these pathogens into the environment. So that would be one of the biggest risks, you would think, somebody might be getting if they consume water contaminated with pathogens.”
To ensure their testing method was giving them accurate measurements of the bacteria load, all the samples were collected and shipped to Winnipeg for testing within 24 hours.
“If you have bacteria in water and they divide so fast, any delay would give you an overestimation of the number so it was critical for us to make sure that everything came back here on time, everything was analyzed within time,” Kumar says. Ideally, the study’s authors would have liked to go back and collect samples at a different time to see if there were any differences but the community’s remoteness made that unfeasible. Regardless, he says, you wouldn’t want to be consuming water contaminated by feces in any amount. “If you’re drinking that water every day and if that water is contaminated for only a week in a year, your health is at tremendous risk.”
Also concerning was the presence of antibiotic resistance genes in the bacteria contained in the water samples.
“We were able to detect resistance genes in most of these samples,” says Kumar. “So it’s not just the mere presence of bacteria, it’s also the presence of bacteria that are resistant to antibiotics so that adds another magnitude to the problem here, to the potential health risk.”
Without clinical data from the community regarding what type of antibiotics are used there and how long infections typically take to go away with treatment, the actual risk posed by the antibiotic resistant bacteria is unknown.
And while the presence of antibiotic resistance genes is a concern, Kumar says it wouldn’t matter if the bacteria were not present.
“You get rid of bacteria from water, you don’t have to worry about resistance genes,” he said. “The bigger problem here is really the presence of bacteria in water.”
The community was notified of the results of the testing before the study was completed and its findings submitted for peer review and publishing.
“We did not communicate our findings to the journal before we had talked to the community,” Kumar says. “They are obviously concerned and it was basically our responsibility to make sure that they were the first ones to know about what we found.”
Given the amount of fresh water in Manitoba and in Canada, Kumar says it is surprising to think that people are drinking unsafe water. The study also shows that water treatment alone is not a solution.
“I think it’s a nationwide problem and this is something that we need to start thinking about,” he said. “I think it’s really important to keep in mind the proper distribution system because this is a perfect example where if you go and test water from the treatment plant you’ll come back satisfied, they’re doing everything that needs to be done, this is perfectly clean water, but it seems like at least the houses that we tested, none of those houses had safe water. As we go forward trying to ensure that everybody in Canada actually has access to safe water we need to make sure access to safe water means access to safe water in my kitchen not in the treatment plant.”
