Cool tips, thanks folks. I may try the fridge thing.. I've been using the same bladder off and on for at least 10 years, and this summer the water tasted a little more funky than I remember. I wouldn't normally care except the kids like to drink from them now too, so which has raised the issue.
99 uzj100, gx470
05 525EXC, 01 XT225, 07 TTR90, 07 CRF50