why separate tanks for grey and black water?

porkslap wrote:
Hi Folks,

Let's say I'm building my own RV. Is there a reason I can't use the same tank for grey and black water?

-Tom

imagining the smell coming up from the sink
:E

As has been mentioned several times, I use the gray to flush the stinky slinky after dumping the gray, so for me, separate tanks are required.

An absolute NO NO is allowing black tank water to come up in the shower floor because the tank is over full due to incorrect indicator lights. We have the gray tank water come up into the shower floor at least once a year. This absolutely, positively requires separate tanks.

We dry camp and are not particularly good at water management. We have a blue tote and dump our gray tank several times in the course of a week. Couldn't do that with a combined tank.

If you forget to check your levels and fill the tank, most times it will fill up your bath first. DW will beat you butt raw if she's in there with a mix of grey and black water because there isn't any room for it to drain.

Thanks from me, too, to all who posted. I learned lots from this thread.

Great thoughts, I appreciate all your insights.

I was thinking about one tank just for space and cost reasons. But I'm starting to think two tanks would probably be easier in the long run.

Thanks again everyone!

-Tom

I like the one tank idea as the black tank is alway needing water. Of course it will all depend on the capacity of the tank.

MM.

Let me repeat something with some emphasis.

You dump the black tank and then run what is PREDOMINATELY SOAPY gray WATER through the drain hose as a rinse-out...

It's a nice feature.

(This and all the other reasons folks have listed make the two tanks a nice way to do things)

We sit in one location for several weeks a time, two tanks allow me to leave the grey open all the time and only flush/rinse the black once a week or so.

TexasShadow wrote:
none other than practical.
gray water can be dumped, sometime, at some places, on the ground, legally, where black water must always be dumped in a legal sewer receptacle.
so sometimes, you can extend your stay at a campground without moving your rig.

This is interesting that it's been mentioned so many times. I've literally never camped in a campground that allowed this.

BB_TX wrote:
There has been a couple occasions when I forgot to check the grey tank level. Backed up into the shower while I was in there. Found myself standing in an inch or two of water. Glad it was grey and not a mix of black.

This alone would be a reason for 2 tanks. This happens to us quite often that we let a tank backup before I go empty them. Having poo-flavored water in any sink or shower would gross me out.

Randu wrote:
Much easier to store and handle a sewer hose that has been flushed out with gray water than one with black.
Randu

If I use a black tank flush, I don't worry about doing gray last for my sewer hoses. By the time that I am done, it's flushing clear water through which is better than the stinky gray tank any way. But, I only have dumped at my full hookup site where I didn't have to worry about time or a line behind me. If dumping at the campground's dump station is a regular thing, this might not be something that you can bank on as much.