Consider this: The average American water park contains 3-4 pounds of fecal matter (that is, poop) in the water. And this poopy contaminant is mostly from adult swimmers who neglect to wipe properly and shower before getting into the pool. (WebND)
Now, chlorine is a fairly powerful chemical that can kill off most germs in seconds, but there are some nastier microorganisms that take much longer to die: e coli, giardia, and shingella are three such frequent fecal contaminants that can end up in the water as a result of swimmers with diarrhea. Cryposporidium is the nastiest little parasite to be water-borne and can live up to seven days in chlorinated pools. (WebND)
The intestinal bacteria, E coli is the most common cause of urinary tract infection. (kidshealth.org)
The pool operations-- the cooling and water uptake-- can weaken the resistance of the mucous membranes of swimmers causing them to become more susceptible to pathogens in the pools. (lenntech.com)
Adenovirus, a group of viruses, can infect the body membranes (tissue linings)including the membranes in the urinary tract. This virus can show up as the same sort of symptoms as a "regular" bacterial-caused urinary tract infection. (kidshealth.org)
The chlorine chemicals, apart from offering some protection from disease-causing bacteria, can themselves create health issues. The June 2003 issue of Occupational and Environmental Medicine talks about a layer of chlorine gas hovering just above the surface of the water that has the potential to damage lung tissue and cause asthma. Indoor pools with low ceilings pose the greatest risk.
Overall, it would appear that the chlorinated swimming pool is a rather hostile environment for swimmers, particularly those with compromised immune systems. If you have recurring urinary tract infections, the Women's Health site of the New York Times suggests that you avoid chlorinated pools altogether.
If you do intend to swim, check into the following recommendations by the Centers for Disease Control:
The best cure is always prevention. If you have a strong immune system-- eat well, follow good hygiene routine, take care of yourself-- you can probably swim in your average chlorinated pool and have little more than red eyes to show for it.