Gray/Black When full

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Gizmo100

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It backs up into the plumbing and that can lead to grey water in the shower pan/tub. And black water will be up in the commode.

This can cause scum buildup in the pipes which will lead to plugged up drains.
 

Gary RV_Wizard

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It doesn't "go" anywhere - it just keeps filling the tank and any associated waste water lines. If waste water continues to be added, it will soon appear at the places where it originates, i.e. sinks, shower and toilet.

The nature of water is that it appears in the lowest opening first, so usually the shower for gray water and the toilet bowl for black water.
 

John From Detroit

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dcrbtt said:
What happens when the Grey/Black water is past full, Where dose it go?

All over.

Gray usually backs up into shower if you have a single gray tank. (I have 2)  On mine the main (Gray) tank serves only the kitchen and half bath lav and it simply stops draining (All are same level) the Wash (Gray 2) backs up into the shower.. only it's empty.

Black.. Either the toilet will nto flush (Sea-land gravity type) or it builds up pressure in teh tank (Macerator-Vaccu-flush types) and when you next flush the gravity.. Well  Think of the movie RV and what happened to Mr. Williams.  Not quite that impressive (Since it is inside). but equally stinky.  In theory it could happen like in the moie just not as far flung.
 

Rene T

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Gary RV_Wizard said:
It doesn't "go" anywhere - it just keeps filling the tank and any associated waste water lines. If waste water continues to be added, it will soon appear at the places where it originates, i.e. sinks, shower and toilet.

The nature of water is that it appears in the lowest opening first, so usually the shower for gray water and the toilet bowl for black water.

Or it could end up on the ground if the tank ruptures which happened to me.
 

Lou Schneider

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The tank itself doesn't have to rupture, just develop a leak where the waste line or vent enters the top of the tank.  Then you'll be dropping the tank to replace the seal(s).
 

AStravelers

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For the gray water, once the shower/tub fills up then it goes all over the floor of the RV soaking the rugs, etc.

For the black water, if you happen to leave the black tank flush hose connected and the water running and you are LUCKY it will just go up the vent pipe to the roof and then run across the roof, down the sides to the ground.  If you are NOT lucky and have a poor seal at the base of the toilet the black water will just seep out on to your floor and make a much worse mess than the gray water.
 

Rene T

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AStravelers said:
For the black water, if you happen to leave the black tank flush hose connected and the water running and you are LUCKY it will just go up the vent pipe to the roof and then run across the roof, down the sides to the ground.

I wasn't that lucky on a fifth wheel I had years ago. The water went up the pipe and when it got to the top it went over the pipe and down the outside of it and right back into the bathroom. Luckily, I had already dumped the tank once or twice so it was mostly clear water.
 

Senator

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Lou Schneider said:
The tank itself doesn't have to rupture, just develop a leak where the waste line or vent enters the top of the tank.  Then you'll be dropping the tank to replace the seal(s).

That is where my grey water went.  Then it leaked under the RV.  It was mostly clear shower water, so not a problem.  It got the insulation wet, so I installed the foil-backed sheet insulation instead.  If it happens again, no issue.

I am not sure why a seal needs to be 100% at the top of the tank.  I could put silicone to seal it, or just cut and replace the seal from the top without dropping the tank. 
 
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