New luxury off grid trailer -- very fancy . . .

If you are serious about conserving water then you use pit toilets and take sponge baths. My wife and I did it plenty of times when we were tent campers.

We each used a one-quart sun shower. We washed and rinsed dishes once a day with less than a gallon of water. It is possible to hold daily water usage only a little more than 1 gallon per person unless you are sweating a great deal.

Also, water from a lake or stream can be treated or boiled.