Contaminants Resulting from Biological Matter in Water - Bacteria and Viruses
The presence of bacteria and viruses in water and the effects
of these microorganisms on the quality of water were noticed
very early in the history of city water treatment. Taste and
odor in drinking water, the clearest indications of contamination,
were attributed to bacterial growth in the water supply (Lingireddy,
2002). City water officials soon noticed that bacterial growth
in water affected far more than taste and odor. Contaminated
drinking water began to be connected to outbreaks of diseases
like cholera
and typhoid.
These threats were quickly diminished when municipal water systems
began chlorinating water in order to kill or inactivate disease-causing
pathogens.
Though chlorinated water has helped municipal treatment plants
fight against waterborne diseases like cholera, typhoid, and
dysentery,
it is not the ultimate solution. It is absolutely necessary
to maintain chlorine residual in drinking water, in order to
prevent the regrowth of bacteria and/or viruses. Ironically,
it is this same chlorine residual that leads to bad tasting
water and respiratory problems.
Also, chlorine is not entirely effective at inactivating all
pathogens. A breakout of disease in 1999, caused by E. coli
bacteria, was linked to contaminated drinking water, treated
with chlorine. Though this particular strain of bacteria is
usually contained in undercooked beef, it can be spread through
water, and it is resistant to chlorine. Exposure to E. coli
bacteria can lead to severe diarrhea and abdominal cramps, as
well as lifelong kidney problems. Gastrointestinal intestinal
diseases, like those resulting from exposure to E. coli
are frequently caused by contaminated drinking water.
Giardia and Cryptosporidium, two chlorine-resistant microorganisms that also cause serious, waterborne diseases, are discussed in further detail on the next page.
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