why separate tanks for grey and black water?

Since most seem to agree that 2 tanks are favorable over one tank. What are your reasons for thinking of using just one tank?

X2 on what NATURIST says - Dump the BLACK first then follow up with the GRAY to clean up things...

jplante4 wrote:

dave17352 wrote:
I agree with all the posters here. Now on occasion I have equalized my tanks when I need more grey water room by opening the grey valve and leaving the black tank valve closed. This brings them to the same level.

I don't see how this equalizes the level. If you were to open both valves and hold the stinky slinky above the top of the tanks, then the fullest tank would sluice into the emptiest tank. Hopefully, the grey tank is fullest.:E

I do this to provide a little extra liquid to flush out the black tank. Be sure to hole the hose high.

I added a third "Main" valve to my dump setup. To equalize the tanks, I just leave it closed while opening the grey and black valves. When dumping, I open the black and main valves, and when the black tank is empty, give it a quick rinse by closing the main valve and opening the grey valve for a couple of minutes before opening the main valve again to drain the grey water.

Some buses have one large single tank. 100 gallon or so.

Black tank waste MUST be dumped into a sanitary sewer of some sort, gray tank waste can sometimes be dumped on the ground without fear of causing a plague.

Some jurisdictions might have different regulations as to where they might be dumped.

And yes, it is much better to dump the black tank, then the gray tank as a first flush of that stinky slinky.

These three reasons suggest that the RV makers, who would surely save the money by having only one waste tank if they could, are right to have two.

Back in the day motor homes didn't have separate black and grey tanks. Only a "waste" tank.

dave17352 wrote:
I agree with all the posters here. Now on occasion I have equalized my tanks when I need more grey water room by opening the grey valve and leaving the black tank valve closed. This brings them to the same level.

I don't see how this equalizes the level. If you were to open both valves and hold the stinky slinky above the top of the tanks, then the fullest tank would sluice into the emptiest tank. Hopefully, the grey tank is fullest.:E

I do this to provide a little extra liquid to flush out the black tank. Be sure to hole the hose high.

It would solve a lot of black tank buildup problems. If you never stay at a place where you can dump grey water on the ground, then I see no reason not to do this.

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

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.

I believe this is the reason and it's regulation not neccessarily a real issue (assuming you drain the tank before it overfills). The govt assumes someone will overfil and it's a sanitation issue then.

Since home built trailers don't have to be inspected (as far as I know), I doubt anyone will come after you if only put in one tank.