I wouldn`t leave the flusher attached. to much of a risk that it may leak into and overflow the black tank! as far as contamination....the flusher has a backflow preventer built into it, or at least it should. It`s easy to install a backflow preventer at the Y adapter.
And I do flush my black tank from the water spigot, the same water source that is used at the dump station BTW! I have a backflow preventer at the end of the hose under the RV, as well as the one that is built into the flusher itself!
I`m still here! and so are quite a few other people too!
