Take jugs of water....I use old milk jugs.
Get a porta-potty....dump it when you get home, or down a pit toilet or dump station if there is 1 in the area.
Use a tree when possible.
Catch all of your sink water in a pan. If it is legal in your area, throw the gray water on the ground away from the campground. If there is a pit toilet nearby, dump it down there. If neither of those 2 options are doable, fill your water jugs back up and dump the gray water down the sink when you get back home.
Use paper plates plates and plastic utensils to save dish water. You will be surprised how little water you can get by with by taking sponge baths and limiting dish washing.
With doing all of the above, you are not putting water in any tank or your water lines. Inconvenient, but doable.
Chap , DW Joy, and Fur Baby Sango
2017 F350 Lariat CCSB, SRW, 4x4, 6.7 PS
2017 Grand Design Reflection 337RLS