Having been involved in an industry where products were designed to carry potable water, I am sure that most people contributing to this thread had no conception as to the testing involved. Each product (say an hose) has to undergo months of testing before it is approved for production. This testing (amongst other things) measures to the most miniscule degree any contamination of the water from constituent parts of the product including fungal growth. This testing has to be done by completely independent laboratories, the manufacturers own figures will not be accepted, by the health authorities.
If someone claims to have discovered a water tank in an aircraft that contains contaminated water, I imagine they also reported the fact both to the airline and Public Health. If true, it would have been stamped on immediately. I do not know for certain, but I imagine that part of a major service would include a close inspection of the potable water tanks. I know it to be the case for the "black water"(sewage) tanks.
I remain of the view that drinking water aboard aircraft is suitable for just that- drinking.
Last edited by Dawdler; 9th Jun 2011 at 15:40.
Reason: spelling