We have a 1978 Royale. It has two tanks which combined capacity slightly
exceed the capacity of the fresh water tank. However, the toilet, lavatory
sink and shower drain into the black tank, while the kitchen sink only
drains into the grey tank. For our particular situation, if the lavatory
sink and kitchen sink would both drain into the grey tank, it would come
just about even when the fresh water tank is empty, then both waste tanks
would need to be dumped. As it stands now, the black tank is often full
when the grey tank is only half full. A larger capacity tank is not the
answer for us. Management of where waste water goes would be a big help.
There is no perfect solution that works for everyone. We take frequent long
trips in our coach, 6 weeks or so. It takes a conscious effort to manage
waste water. Just our situation. Yours might vary, but packing around a
heavily laden waste tank burns fuel. Just some food for thought.
Jim Hupy
Salem, OR
78 GMC Royale 403