There's a whole topic on propane usage, or use the googler. .5-.7 gal of propane per hour for the genny.
Water? Unless you're into making heated wet wipes in your microwave, 5 gal/day/person is reasonable/plenty for dishes, little cooking and a hot navy shower.
Depends what you're doing, IMO. Camping trip in the great wide open (what you're probably asking about with H20 and propane usage), I'm good with a 2 gal shower to knock off the dirt.
Living in it for work for weeks, I can't really subscribe to "survival camping" mode of operation. If I can't live "normally" then I should rent a room or apartment or something.
Bottom line it varies greatly. Camped next to a dude this summer who had twin chit tanks and twin gray tanks (big toyhauler). Him, his wife and kid couldn't go more than 3 days without calling for the turd burglar to come empty their tanks.
So you have to figure out how much you need. No right answer.