My daughter came up with a saying:
"If it's yellow let it mellow, if it's brown flush it down".
That philosophy has helped us considerably since our leach field here at home got breached and we tend to have overflow from the tank go into the ground about 100ft away. We live in an agricultural district on 4 1/2 acres so we haven't gotten around to putting new field in yet.
We have a jabsco toilet for the bus. It's a marine toilet and has the wet dry feature (add water when taking a crap and leave dry when peeing only.
It has the good ole hand pump to pump in as much water as we need to flush it down when we chose. I think it's a great water saver for the bus. If anyones interested I can run out to the bus to get the model #, we bought it brand new off of CL for a $100 bucks from a guy who changed his mind and bought a smaller one for his boat rebuild.