Originally Posted by 16ACE27
The bathroom sink DOES drain to the black tank. It adds more water to the tank that needs it to flush out the contents. Most people run out of grey tank volume due to showers long before they run out of black tank volume. Putting the bathroom sink in the black tank helps even that out as well.
Our bathroom sink drains to the black tank also... verified by laying under the tank with the bath sink running. IMO, it's a poor design... maybe to save Thor a few bucks in labor and materials? Who knows... In an emergency, you can bleed some gray water... not so with the black. There are even open concrete catch basins for gray "camp water" in many parks.
I ALREADY put sufficient water into the black tank to keep it "liquid". I surely don't want to needlessly add excess water to take up space in an already smallish tank. So on long trips we wash hands, etc. and brush teeth in the kitchen sink to avoid filling the black tank. That's just ridiculous!
So... there is NO EXCUSE for piping gray water to the black tank. Lazy, cheap decision! Just educate your customers and let them decide.