Clearing up a cloudy issue concerning pool water

Whenever a person swims in a pool, bacterium and viruses from their skin and hair (not to mention any incontinent accidents) are left behind and the vast majority of these microbes will be eradicated by the chlorine (Cl) in the pool. The bacteria, which live on the skin of healthy people, are not necessarily harmful unless the person already has lowered immune defenses. Those who typically fall into this category include young children, seniors, pregnant women, AIDS patients, and those on immunosuppressant medication.
It is not unusual for DNA probes of swimming pool filters to find bacteria as common as P. aeruginosa or Escherichia coli (E. coli) given the former lives on most surfaces in civilization, while the latter is present in microscopic amounts on everything one would touch after going to the washroom.
It should also be made clear that there is a small sub-group of E. coli that is responsible for severe illness, resulting in vomiting and diarrhea, called E. coli O157:H7. These bacteria make people sick, and, if found in a pool filter, it would indicate a swimmer(s) was sick with the above symptoms when they went swimming. Almost any other E. coli contamination would simply indicate swimmers were not cleaning themselves thoroughly before using the pool, and while this is unsanitary, it is not a cause for alarm if the pool is properly chlorinated and maintained.
Knowing the difference between each strain, it can be considered that the Centers for Disease Control and Prevention (CDC) report on “Microbes in Pool Filter Backwash,” did not find any traces of E. coli O157:H7 with the DNA probe, but did find other non-specific E. coli. This shows the contamination in most pool filter samples was the result of dirty swimmers—not because severely sick people contaminated the entire pool, thus making it dangerous for all other swimmers.
Further, in the case of either E. coli strain, chlorine will kill whatever is floating in the pool as long as the sanitizer levels are kept appropriately high. Proper chlorine use is vital to keeping pool water clean, safe, and free of infectious microbial contaminants.