Can you refill an aero water bottle on the bike?

[Wahine]

For years I wondered what the sponges were for! Now I get it! Thanks!

Is that their only purpose? Silly me thought they were to give the straw some room to move.

The sponges also dissipate the movement of the liquid in the bottle, thereby preventing it from slopping out the top so easily when you hit a bumpy bit in the road. They are very effective.