Which pipe is which????

RoyB wrote:
Probably the only sure way would be go up on top and take a big whiff of it...

You can always call the manf with your VIN number handy and ask them.

Roy Ken

And the one that stinks LEAST, more often than not, is the black tank.


Here is a positive way to do it....

Get one of those clear extensions so you can see the dump and put it in line with your hose.. I like to put it at the RV end.

Dump tanks and CLOSE VALVES.

now, take a couple gallons (or a hose) up on the roof with you and run/pour some water into ONE of the vents, Just one, not both.

Go back down and open first the BLACK tank, if it dumps a bunch of mostly clear water.. You have a lead.

Then open the gray, if it dumps nothing, You have your answer

On the other hand if the black tank dribbles and the gray gushes.. Well, then you have the other answer.