With my trailer, the fresh is 20gal but only holds about 15-18gal. The gray is 20gal and I have a cassette toilet.
That's the camper I take on sightseeing trips. I use campground facilities for showers. Only use the cassette toilet for nights and if going to the facilities is inconvenient. A 6gal grey tote and six 2.5gal aquatainers (filled at home).
That gets me through about 8 days without any other water conservation.
I usually use one aquatainer for pet water bowls and one for my drinking water. The other four are used to refill the tank. I have a long large funnel (advertised for frat parties on Amazon) for filling. It works great.
