Dirt from the rear wheel?

Placing water bottle with push-pull lid/cap on the rear end of a bike could get very dirty under the rain or paddle in muddy terrain, while not a concern for those who have installed a rear fender or rear rack with top carrier bag.

If you don't like adding a fender, and no need to access water bottles on your back during paddling, use bottles with dust covers or dirt caps will be the easiest way to keep the bottle lid clean from dirt.