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Old 04-09-2012, 08:05 AM   #1
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Black tank overflow

Went camping for Thursday --Sunday this weekend and encountered a problem with the black water tank overflowing. I'm not sure but I think this tank, 2005 Grand Surveyor, is a 30 gallon unit. We were using the bath/shower house at the campground for everything except nightly visits to the camper head. Late Saturday evening there was a litte water on the bath area floor, liquid was dripping from the rear of the camper (rear bath), and that bad smell. I immediately started the black tank to drip for just a few hours (I know it's not the thing to do) as I had to lower the tank level. I did a full dump Sunday morning but there was hardly any water to come out of the black tank. I also dumped the grey tank and it was almost full. Now-I'm sure there is a seal under the toilet and I should replace it. How do I treat the floor of the bathroom to assure there is no funky stuff growing and no future smell? I just hope this one time didn't ruin the floor. Of course my gauges read "full" even when the tanks are empty. And another thing--why don't the black and grey tanks have some type of "overflow" line to prevent this? Thanks for any info. David

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Old 04-09-2012, 08:25 AM   #2
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Water backing up into the shower pan is gray water.
It is your "overflow" warning.
Gray water DOES smell and is often confused with black water (which smells worse BTW)
Your black tank most likely was not the problem.
Gray water almost always fills up before black.
There is a "technique" (technique only) that is way safer than dumping black or gray water on the ground. Big fine in most states if caught BTW.

If you buy an "end shutoff valve" like Valterra T58 Twist-On Waste Valve: Automotive , you can use the dump mast to transfer gray water into your black tank to extend your time before dumping. Obviously you must wait until the gray tank is nearly full when you do this to make sure the water flow is FROM the gray tank into the black tank.

The correct technique is:

1) Dump mast end valve CLOSED and capped
2) Open Gray water valve all the way
3) open black water valve slightly and allow the gray water to flow into the black tank
4) Close the black valve
5) close the gray valve

The MOST you will transfer using this "technique" is about 10-15 gallons; buying you a day or two on your spot (or Blue Boy trip). Remember the dump mast will be full of gray/black water when you do dump from the dump mast! Do not open the mast end valve until your hose is connected to the Blue Boy or dump station.


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Old 04-09-2012, 08:48 AM   #3
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I understand the "technique" and appreciate the info. I had not thought that grey water would have such a smell but suppose it could. Also- I do have the portable tank (Blue Boy?) which I will always take with me from now on. Now--"IF", and I'm not saying it was not the grey water, why would the bad water be coming into the bath area floor via the bottom of the toilet? I have considered the possibility that there "could have" been some transfer due to leaky valves between the grey water into the black water tank and this is what caused the overflow. There was a lot of dish washing on Friday night as it was my turn to feed the group. I now have the unit tilted way back to help drain any residual water and will investigate all of this when I get home today. Thanks, David
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Old 04-09-2012, 09:24 AM   #4
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You could have a leak in the plumbing under the shower. On my first trailer, the drain plumbing under the shower, because of vibration or something came loose and in one area, the pumping actually cracked and was leaking slowly.

Just some things to check out.

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Old 04-09-2012, 12:27 PM   #5
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Something else to check. By opening the black tank valve slightly to drip out, you may have de-watered the black tank leaving solids. The only way to know for sure is to back flush the tank or use the black tank rinser along with a clear elbow next time you're hooked up to a sewer connection.

I can understand a poor toilet seal causing odours but not water on the floor unless the tank level was above the seal as there's no trap on the toilet.


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Old 04-09-2012, 08:00 PM   #6
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Thanks Dave, I was aware of "de-liquifying"the black tank but had to try something and quick. After reading all the posts I'm now believing I had a grey water crossover into the black tank via leaky valves. I know the grey and black tank dump valves leak a bit, so they could have crossed-over. Now, as to why/ how the water backed up enough to come out under the toilet--I don't know. My biggest worry at this time is the flooring. I hope I caught this in time to prevent damage. New valves,new toilet seal, good inspection, and hood cleaning to be done soon. Thanks for all the info.

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