All I'll add is there's a big difference between a survival situation and expanding one's outdoor travel envelope. Anybody who does small craft ocean touring should have some knowledge of how to distill small amounts of freshwater to enhance survival chances if things go "pear shaped." And small amounts is what you'll get from simple stills.

This is quite different from extending the number of days one can travel without resupply. I budget a gallon per day per person for routine backcountry hiking and camping, half that if dry camping and lugging my water a distance.

Happy experimenting.