There are a lot of containers for water that are sold for tenting camping. I use to have one that rode on top of the car long ago when I tent camped. Friends of mine use to buy a new galvanized trash can each year and fill in with water for camping. Water has to have some bleach in it but it works. Ten gallons use to last us all weekend for dishes, hands, etc.
Happy trails........................
Sue and Ed Rowe
Hemet California
2005 3400RL
2006 GMC 3500 Dually, D/A, Crew Cab, Long Bed