I usually put one of propel drink mix things in my 3L just to add a little taste, but after i ride, i usually rinse mine out a couple times, dry the heck out of it (even use a hair dryer) and then stuff a couple dish towels in it just to keep it open until the next ride.
i’ve been looking at those "official" cleaning kits at pricepoint for $14 bucks… are those really worth it?