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demijac · 11-10-2015, 11:34 AM

How would you explain this strange occurrence?

A couple of weeks ago, we were doing our usual weekly black tank 'empty and rinse' maintenance routine. After first emptying the black tank, we began filling the black tank (which usually takes about 15 minutes) with water to get a good rinse. This time, about ten minutes into refilling the black water tank with water, we noticed brownish water streaming down from the roof on both sides of the trailer towards the front. I'm pretty sure it was rinse water from the black water tank due to the light brown color and white bits but can't say for sure.

Can anybody explain what happened? Once, when filling the black water tank with water to rinse it, we over filled and the overflow came up through the toilet inside the trailer. That did not happen this time and there were no visible leaks inside the trailer so we're hesitant to say that the cause was overfilling the black tank with water.

Our biggest questions are .... how does water get to the roof of the trailer? .... and what happened and why?

Thanks.

nrgtrakr · 11-10-2015, 11:35 AM

Tank vent overflow ...

Lily&Me · 11-10-2015, 11:37 AM

markdoane · 11-10-2015, 11:42 AM

What are you using to re-fill the black tank? Sewer Solution? Tank Tornado?

Sure sounds like a vent overflow.

IanPoulin · 11-10-2015, 11:49 AM

In my manual it says to only ever run the tank flush with the black tank gate valve open. I would assume this is one of the two possible bad outcomes if you don't?

Foiled Again · 11-10-2015, 11:53 AM

Quote:

Originally Posted by nrgtrakr

Tank vent overflow ...

All plumbing needs roof vents - mainly to carry away sewer gas - which can be nasty even from a gray tank or sink drain, and is worse from fermenting human waste. The gas in the black tank would build up pressure and eventually pop the seal on the flusher if it couldn't just bubble out of the air and into a vent stack. And the smell when flushing - about 10 times worse than it already is. You filled the tank until all of the air was exhausted, then continued to fill the vent and finally the vent is filled and - you have a waterfall!

Congratulations (sort of) it beats flooding the inside!

Paula

greghoro · 11-11-2015, 11:09 AM

I'm not surprised it didn't come up through the toilet (flap saved you there) but am surprised that it didn't come up through the bathroom sink drain.

Most black tanks on newer Airstreams service both the toilet and the bathroom sink. Not sure about yours. But if it does, you were fortunate to have the sink drain closed.

Greg

J. Morgan · 11-11-2015, 11:22 AM

Some water supplies are higher pressure, some lower, some are capable of more flow, some less, so flow rate can be variable.

You filled the tank, and then some fast.

Good thing you didn't flush the toilet in the middle of this mishap or you might have gotten a very unpleasant shower.

Brevi tempore!

Protagonist · 11-11-2015, 11:51 AM

Quote:

Originally Posted by Foiled Again

All plumbing needs roof vents - mainly to carry away sewer gas - which can be nasty even from a gray tank or sink drain, and is worse from fermenting human waste.

From an engineering standpoint, that's not actually the purpose of the tank vents, otherwise your fresh tank wouldn't need to be vented.

Basically an "empty" tank is full of air. When water runs in, the air has to come out. When you empty the tank, air has to get back in. THAT is what the vents are for.

However, it is true that air from the waste tanks can be smelly and unhealthy to breathe, and that's why the vents go through the roof, so the smell doesn't get into the trailer.

But getting back to the OP's problem, if nothing else he managed to perform a successful tank pressure test, because if the black tank didn't leak under the pressure of several feet of water column, it's certainly not going to leak under normal use.

J. Morgan · 11-11-2015, 12:53 PM

Quote:

Originally Posted by Protagonist

But getting back to the OP's problem, if nothing else he managed to perform a successful tank pressure test, because if the black tank didn't leak under the pressure of several feet of water column, it's certainly not going to leak under normal use.

True dat!

Brevi tempore!

Wayne&Sam · 11-11-2015, 02:09 PM

And for the moment anyway, it's REALLY clean.

tjdonahoe · 11-11-2015, 03:28 PM

I watched a movie about a family in a motorhome that something like this happened to...never thought it would actually happen!..

WestieHouse · 11-12-2015, 06:50 AM

It is good when we learn from our mistakes. It is even better when we learn from others' mistakes. (Some my own appear in other threads.)

tjdonahoe · 11-12-2015, 07:02 AM

A fellow I know hooked his hose up, water is on and valve is closed, started talking with the neighbor when he heard a Big Bang , what was that? The water pressure did not go up the vent pipe, but blew the glued on top of the tank off, he had to clean everything and re glue it....it was a 5th wheel trailer so he had plenty of room from the bottom..........

Protagonist · 11-12-2015, 10:25 AM

Quote:

Originally Posted by tjdonahoe

I watched a movie about a family in a motorhome that something like this happened to...never thought it would actually happen!..

Ah, yes, the classic "RV" starring Robin Williams. Buy a copy, carry it in your Airstream, and watch it at least once a month as a reminder of what NOT to do.

streaminwild · 11-12-2015, 10:50 AM

Quote:

Originally Posted by demijac

How would you explain this strange occurrence?

A couple of weeks ago, we were doing our usual weekly black tank 'empty and rinse' maintenance routine. After first emptying the black tank, we began filling the black tank (which usually takes about 15 minutes) with water to get a good rinse. This time, about ten minutes into refilling the black water tank with water, we noticed brownish water streaming down from the roof on both sides of the trailer

Thanks.

I would fill for 9 1/2 minutes from now on. Your toilet seal has been pressure tested as well. I don't even want to think about what could have happened

...too late

tjdonahoe · 11-13-2015, 06:49 AM

Now we all learned something, Leave the damn drain valve open....

msmcv51 · 11-13-2015, 10:12 AM

Where do you put water into a black water tank other than the toilet. I can not find another place on our 1987 25 footer.

Protagonist · 11-13-2015, 10:17 AM

Quote:

Originally Posted by msmcv51

Where do you put water into a black water tank other than the toilet. I can not find another place on our 1987 25 footer.

1987 models might not have included black tank flush fittings. I don't know the year they were first introduced.

macofpei · 11-13-2015, 11:06 AM

At the campground I stay, all summer, a few years ago, a seasonal decided that he had to flush out the black tank. There were 4 adult persons using the bathroom and the main drain was always left open. You probably know what happened and why they had to flush out the tank. Anyway, the father hooked up the hose and closed the main flush valve and started to flood the tank. After awhile, the son went into the bathroom and wanted to see how the tower of stuff was doing (;-) When he stepped on the flush valve, the full pressure of everything in the tank came exploding straight up into his bent over face. Stuff was everywhere.! He came staggering outside wrenching, and in total dismay. The considerable crowd all starting laughing and he got told that wasn't the way to get sh1t-faced. His mother spent several hours cleaning everything up and they learned that the main Black Tank drain needs to be closed most of the time, only opening to empty the tank. I wish we had it on video.