2nd grey tank mislabeled?

[ManitobaRambler]

I have a 315BH, it supposedly has 1 black and 2 grey tanks, according to the gauge panel and exterior stickers. However, it appears the rear toilette flushes into the rear Grey tank. The gauge for this tank is label as Grey#2, and the outside pull valve and hose connection labels it as Grey#2. Is this normal? I am currently treating the rear grey tank as a black tank, but would like to know more. The dealer thinks they just used a "universal" or common monitoring panel but they should have at least put a different sticker outside, knowing one of the toilets empties into it. I have filled and emptied all of the tanks separately and determined that the shower, front washroom sink and kitchen sink fill the Grey#1 tank. The front toilet fills the Black tank. The Black and Grey#1 drain valves are located together closer to the front. The rear sink and toilet fill the rear Grey#2 tank, with the separate drain and valve near the rear, but is this actually a black tank. Are black and grey tanks built differently?

 

[taskswap]

Unless they went with something special, most tanks are all the same, just a blow/rotomolded plastic tank with a few flat spots for fittings to be installed. They're often even the same for black, grey, and fresh water. Plastic is plastic. Honestly, the only real reason to keep them separate is there are often times you can dump your grey water but not your black - at Lake Mac in NE they have no septic at the sites but you can dump grey because it's just sand and it filters it almost immediately. (Also there's the trick about dumping your black first, so when you dump your grey it helps rinse out the hose...)

I've even heard of transfer kits that let you transfer some grey into black so you can last longer while boondocking, because for some reason RV makers always seem to use the same size tank for both grey and black, even though grey usually fills up 3-4x faster. When we boondock we often dump things like leftover pasta water into the toilet to save space in our grey...

Labeling, however... we have the exact same issue on our 386BH. Our front grey tank is labeled "Black #1" and our front black is labeled "Grey #1". I suspect whoever put on the labels got mixed up. We're just waiting for them to fall off - I won't bother re-labeling them . It's really easy to tell the difference when opening a valve because the grey tanks are like 1.5" pipe and the black are 3" (unless you have remote valves...)

Maybe you got the same label-guy at the factory that we did...

 

[2019_V22]

In short, my tanks appeared to be mis-labaled on the outside, but were actually correctly labeled. After a little investigation, I found that they improperly installed a grey tank under my toilet, and the black tank for my shower/vanity. While this works, it sort of doesn't. My toilet tank is a difficult to flush clean, I see that black tanks are mainly pitched or bellied toward the drain, and grey tanks are more flat bottomed. I confirmed this with my tanks when I lowered the coroplast to understand what was going on.