I think there should be a way to refill yur water tank in the Rover, just like you can store extra batteries and plug in the oxygen there should be a way to refill w small/medium/large water tank in the rover, that you can refill your water from. For instance say you built awell on one of your outings and upgraded it so that you ca get oxgen. you should then be able to refill, oxygen, water and engery at that point as long as there was a solar panel.