We have two 45 gallon tanks and 2 of us. We usually get about 10 days with average use. We use campground showers when possible but rare to use campground toilets. I have external sensors on my tanks that seem to work rather well. We try not to skimp of water in the black tank. The more water you keep in it the better it dumps and stays cleaner. When we leave to come home I usually dump my tanks and add about 1/4 tank of water to the black tank to slosh on the way home and have a dump station here at the house to dump in when we get home.
