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grey and black tank overflow problem

August 20, 2014, 07:29:14 pm

A friend decided to help dump my grey and black tanks while I was dealing with another problem away from the coach.  They connected the water hose for the washout and turned it on without opening the dump values as instructed by the
the warning sign above the intake.  I returned to find a great deal of water on the ground under and around the coach.
Luckily the black was almost empty to start so  the overflow was not totally disgusting.  I turned off the water and  dumped- of course there was a lot of clear water in the tanks
 I don't know much about the plumbing for the tanks.  Is there an overflow valve or did the water pressure tear a hole in something?  I didn't have time to investigate then but would appreciate any info.
Thanks

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Re: grey and black tank overflow problem

Reply #1 – August 20, 2014, 08:35:47 pm

There is no such thing as an overflow valve on the grey or black tanks. There is an overflow/vent that runs over the bulkhead in front of the passenger side dualie for the fresh water tank which also serves to let air in to replace the dispensed water... When the waste tanks fill up to overflowing, it will start filling the vent pipes and the drain pipes in order from low to high. the shower drain will start to back up first on the grey tank and of course the toilet for the black tank. That assumes a perfect seal around the waste and vent pipes to tank interface, which are just sealed with a rubber grommet at the top of the tank. It would likely seep out around those joints as the level rises above it. That will run down the sides of the tank behind the utility bay wall and try to find an exit at the lowest point. Not to big a deal unless there are un-caulked penetrations in the basement floor as the liquid will infiltrate into the basement floor insulation and framing. Probably a good idea to open up the utility bay wall and inspect, if you don't already have an inspection/access hatch. Dry it as well as you can and provide a fan and maybe some heat to help dry it out. Just my opinion...
edit: There won't be pressure built up from over filling the tanks (waste or fresh) except an area where air might be trapped at the top of the tank. That could cause some bulging at the top and possibly move the seal on the vent or waste pipes (not present on the fresh tank). There water would just keep rising up the vent pipes until spilling out on the roof, in the case of the black tank, assuming that the toilet flap valve was well sealed. In the case of the grey, it would be spilling out on the bathroom floor. Not a pleasant thought in either case, but it is not going to rupture a tank. Mind you, my first hand knowledge is based on our 99', but I don't think yours are different in principle.
Don

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Re: grey and black tank overflow problem

Reply #2 – August 20, 2014, 10:32:14 pm

Not long ago someone overflowed their black tank which push liquid up the vent pipe that goes from black tank up to roof. Only small problem was the roof part of the vent pipe was not connected lower part and fluids flowed out over the drop ceiling and ending up totaling the coach.

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Re: grey and black tank overflow problem

Reply #3 – August 20, 2014, 11:21:59 pm

I overflowed the Black tank one time.  Had the flush flushing and the gate valve closed.  I flush the Black tank 2 to 3 times every time I drain that tank.  My DW called me when she started to see water on the floor by the bathroom.  I quickly turned off the water for the flush and ran inside.  Luckily I had already drained the tank and was flushing the system.  We do not know if the water was coming out of the toilet or not.  The overflow fro the Gray tank is the shower basin. 

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Re: grey and black tank overflow problem

Reply #4 – August 21, 2014, 12:21:37 am

One disadvantage of tank flushers. You are not the first Scott to leave them on with gate valve closed and forget to open gate valve. Use with caution. This is how someone determined that their vent 0pipe was not connected to roof.

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Re: grey and black tank overflow problem

Reply #5 – August 21, 2014, 09:29:44 am

Hate to admit it... When I first bought 95 U280 I went to fill the freshwater tank,  waited.. and waited.. and waited, nothing out the overflow as I expected,  then...... water flowing out of the toilet.  I had used the flusher connection thinking it was the fill, and the way it was labeled it sure looked like the water fill.  Luckily tank was clean and I was able to dry out the carpet before any damage was done.  If there is a way to screw something up I have done it and sometimes twice.
Gary B

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Re: grey and black tank overflow problem

Reply #6 – August 21, 2014, 10:56:48 am

True confession... I've done this more than once. Usually happens when I walk off to talk to the neighbor. Next thing I know there is water running down the side of the coach and DW is yelling that water is coming up the toilet! Luckily it's only happened after I've already flushed the tank at least once.

I'm no long allowed to flush the black tank unless I'm standing there the whole time. I now bring a chair out and sit next to the wet bay until I'm done flushing...

see ya
ken

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Re: grey and black tank overflow problem

Reply #7 – August 21, 2014, 11:26:49 am

Not exactly related, but I once ballooned the fresh water tank on my SOB.

The only overflow for the fresh water tank happened to be the fill hose.  I had the white water hose stuck in the fill opening and for distracted while filling the tank.  Came back to find water squirting out the small opening around the water hose and shut it off.  When I removed the hose, water gushed out.  Went inside to discover the floor above the water tank was buckled,  opened the bay door to see the water tank bulging on all sides.  Insurance paid for a new water tank and putting the floor and cabinets back in place.

Oops.

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Re: grey and black tank overflow problem

Reply #8 – August 21, 2014, 03:56:57 pm

Sounds like another episode of the movie with Bobbin Williams-"RV" can come from all this!
Ed

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Re: grey and black tank overflow problem

Reply #9 – August 21, 2014, 04:44:00 pm

Ed, I bet if you videoed all the mistakes and screwups that all of us have made ( except you of course ) thru the years you could make several movies.
In fact with all the REALITY stuff on TV I am amazed that someone has not made " THIS IS RV'Ing " as a weekly show.
Maybe too tame for today's audience.
Gary B

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Re: grey and black tank overflow problem

Reply #10 – August 25, 2014, 11:32:08 pm

Well, as usual I learned a lot from the forum.  Thanks a lot.

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