I'm researching to tour cross country in a couple months. I'm trying to pack light. I probably will only use rear panniers and not front. Then the thought came to mind. Are there panniers built specifically to just carry water while touring? It could be something useful. Only problems I see is that water is not very light and it could add a good amount of weight. So climbing with them could be hard, but people climb heavily loaded anyways. Another problem I see is that the weight would easily shift. Perhaps they would work better on the rear and leave the solid stuff in the front at the steering.
Anyways, are there water panniers out there? TIA. Matt