Meant to post 3 links:

http://www.ag.ndsu.edu/news/newsrele...t-is-bacteria/
The bacteria are difficult to remove completely from your home, although the stains are removed easily with a general-purpose cleanser containing chlorine bleach. You also may add ¼ cup of bleach to the toilet tank, let it sit for 15 to 20 minutes and then flush the tank a few times to remove all of the bleach. Do not leave bleach sitting in your tank because it will damage rubber valves and seals.
(that's about ~250 ppm chlorine -- you can't go that high in your pool)


http://www.myarestin.com/periodontit...-bacteria.html
Specific bacteria called red complex bacteria (RCB) are strongly associated with periodontal infection. The RCB are: P gingivalis, T denticola, and T forsythia
ooh! In your mouth!


http://en.wikipedia.org/wiki/Serratia_marcescens
S. marcescens can cause infection in several sites, including the urinary tract, respiratory tract, wounds,[3] and the eye, where it may cause conjunctivitis, keratitis, endophthalmitis, and tear duct infections.[6] It is also a rare cause of endocarditis and osteomyelitis (particularly in people who use intravenous drugs recreationally), pneumonia, and meningitis.[2][3] Most S. marcescens strains are resistant to several antibiotics because of the presence of R-factors, which are a type of plasmid that carry one or more genes that encode resistance; all are considered intrinsically resistant to ampicillin, macrolides, and first-generation cephalosporins (such as cephalexin).[2]
As Kelemvor notes, S. marcescents is an oft-suspected culprit. As you can see, it's not really benign.