Didn't think of a well, that's a cool idea !
You implemented a similar system with the berries and fishing - they allow farming of food for the tradeoff of time and energy - so I was trying to think of a plausible way to make gathering water the same instead of relying on random chance :) Maybe a well could provide 1 water, and a bucket could increase the efficiency to 2 water, then allow the player to start hoarding water for the journey off the raft?