Plumbing Schematic for "Y" Valve

[SolaceinOly]

Hello everyone. i'm looking for some routing ideas for my current project of replacing my holding tank. I would like the option of draining off my tank (when offshore) without the use of another pump. Would the use of a "Y" or a tee in the pumpout hose connected to my thru hull discharge vaive allow me to drain off my tank? (when offshore) Any suggestions would be great....

[sundown]

Here is a web page with a bunch of ideas.

Holding Tank Plumbing and Layouts | Tek Tanks