33gal freshwater, about how long will it last?

Three, maybe four days with showers for the two of us every other day. When you go to take a shower, run the water into a clean pitcher until it gets hot enough to get into the shower. Save the clean water for other things.

After doing dishes, dump the soap water down the toilet. You've probably been conserving water so the extra water with the soap in the black tank will help it and keep your gray tank from filling up too fast.

Bill