I have found some folks adapt to dry camping easily, and others don't
. And you learn how to better conserve water as you go.
My wife and I mainly boondock and use around 90 gallons a week. We use the water in the tank for daily showers, dish washing, and toilet usage. We have friends that use less than that per week, but we enjoy showers, not sponge baths
When my BIL and SIL join us in their RV, they just never get dry camping. They use about 50 gallons a day so he is always refilling the fresh tank and emptying the gray tank.
Hopefully the offending members of your party can adjust their RV water usage habits
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder