I think I've seen a thread like this previously, but can't remember the answer.
Last year I started using a water bottle (one of those proper ones shaped to fit in your hand). Everything was fine until I did two training runs in the space of a couple of weeks, of about ten miles, and only just made it home. Let's just say that say that one run lead to another, if you get my drift! I stopped using the bottle and subsequently did equally long training runs and then a couple of half marathons, and the internal plumbing gave me no problems, so I can only assume that there was something sinister in the bottle. I tried washing up liquid, (thoroughly rinsed, of course), but want to start using the bottle, or a new one, again. Am I right in thinking that those tablets for cleaning false teeth are a good idea, or does someone have a better idea?