Why two tanks?

[SuwanneeDave]

Maybe it has to do with weight distribution but I am wondering why there are separate grey and black water tanks, when they are both emptied into the same sewer dump.

[Koop]

Sanitary reasons. You don't want black water on the same line as your kitchen sink for example. I know, your S&B home has one outlet line, but it isn't a closed system.

[FlyingDiver]

Not all RVs have two. The big Prevost conversions only have one, with a gray-water bypass system for when you're connected to a sewer.

[Hooligan]

It is handy to flush the drain hose with gray water after emptying the black tank..

[Doggy Daddy]

Also, your grey water valve can be left open when hooked up to the sewer and city water, so hot showers can be lengthy.

[Caveman CBB]

I think there was a thread on this asked on this site just not to long ago.

[MSHappyCampers]

Originally Posted by Doggy Daddy

Also, your grey water valve can be left open when hooked up to the sewer and city water, so hot showers can be lengthy.

That's a "biggie" for us! We never use the CG bath facilities so the gray tank fills up real fast! Also, having a combined tank would take a lot of chemical (if you use them).

[Clay L]

I suspect the main reason is so that if you are not hooked up to sewer and fill the tank up while taking a shower you won't be standing ankle deep in water containing fecal material.
Gray water coming up in the shower smells bad but is better than a black/gray mix.

[wincrasher]

Actually I think it is mainly the space available to put the tanks. Remember you have a frame under there that you have to work around. Two thirty gallon tanks are alot easier to place amoungst the structure than one sixty gallon tank. You also can opt to have odd sizes - say a 30 gallon black, but a 40 gallon grey.

Also, they like to place a mechanical toilet directly above the black tank. That way it just drops right in. So that gives you more flexibility on where you can place sinks, not having to have a clear route to the black tank for the drain.

Personnally, I'd never buy an RV with a combined black/grey tank. I've filled my grey tank on occassion and only discovered it when I was standing in the shower wondering why it wasn't draining. I am not taking the risk of standing in my own poo!

[Rich and Cork]

I remember some years back a friend's motorhome allowed him to co-mingle the contents of the two tanks. He had quite a shock when **** came up the shower drain.

[DaveTN]

Originally Posted by MSHappyCampers

That's a "biggie" for us! We never use the CG bath facilities so the gray tank fills up real fast! Also, having a combined tank would take a lot of chemical (if you use them).

Agreed - if we all take a shower (5 or 6 of us), grey tank is full.

[Dog Folks]

No too many years ago you could dump grey on the ground in some places.

There are still places that allow it today but they are shrinking fast. Never black.

Some parks even had grey water dumps located throughout the park on the side of the park roads but only one dump station for black.

[DaveTN]

Originally Posted by Dog Folks

No too many years ago you could dump grey on the ground in some places.

There are still places that allow it today but they are shrinking fast. Never black.

Some parks even had grey water dumps located throughout the park on the side of the park roads but only one dump station for black.

Park we camped at this past weekend had a grey water dump in the middle of a crowded area. I would not want one of the sites next to it. That was the first grey dump I had seen in a while. It's always funny when I take an early morning walk and see a huge wet area next to a rig, lot of folks dump grey water illegally or not.

[tuffr2]

Lots of times I get back from a hike of bicycle ride sweaty so I will rinse off and wash my hair with the outside shower. I guess that water would be considered lite gray.