I clean mine when needed (once/year or less) with a dab of bleach and water. When not in use, they stay in the fridge in a giant zip-lock bag. No nasties. For just a funky taste, I'd try the baking soda. I've been a cyclist for so long, drinking out of plastic water bottles and hydration packs, that I think water that doesn't taste like plastic tastes funny. :^)
Kathy