this morning i've been thinking about how to make things if i was sent back in time. i was researching soap, and how to glaze pottery, but the most immediately pressing thing would be getting drinkable water.

once you have time to make a ceramic vessel, you could boil water forever and always have clean water, or make some sort of clay alembic to distill sea water.

but, in those first few days, how could you get clean water? assume multiple possible environments, like in grasslands of america, in tropical forests, near the beach, etc.

i just think that you're going to have to drink from a freshwater stream or something until you find a way to make a clay pot.