This seems like a stupid question.
Up to now, Dd has had a cylindrical plastic water bottle.
When washing up, I can get my hand inside with a washing up sponge to get it clean - or it can go in the dishwasher.
Now Dd wants a metal bottle with a tapering neck (Chilly's).
Am I missing something - how do you get a sponge in it to wash it properly? They don't seem to be dishwasher safe either.
Everyone seems to have them, so clearly they must be cleaning them somehow.