How NOT to run a black tank flush

[Kaadk]

Well, this weekend proved to be an 'interesting' event. Let me prefix this by saying that I've learned my lesson:

Do not leave a hose hooked up to the black tank flush and just 'trust' that nobody will turn the water on.

So, time for the story:

Yesterday morning our tanks were full, so I dumped, flushed, etc... to have room for the rest of the camping trip. We were only staying one more night so I didn't bother to unhook the x-hose I use for the sewer flush. I just turned the valve to shut off the supply. I figured the next day I'd be able to just turn it back on when I flush the tanks a second time.

Later that night I was just getting some dinner cooking on the outdoor stove when my wife stated "Where's that water coming from?". Never a good sign to hear that. It appeared to be coming from the bathroom, which my son had been in just a short while ago. Since we've already caught him once closing the drain in the sink and then leaving the water on, I assumed he did it again and it overflowed. Great! Just what I need to deal with.

While, since I was getting the food going, my wife decided to go in and check on it. From inside the trailer I hear the scream "Shut off the water! We've got a geyser!" I immediately flip off the gas supply, run around the trailer and kill the water at the tap. I then fly back into the trailer, shouting at the kids on the way to remain in their chairs and not go near the stove. Bolting into the bathroom I ask my wife where the water was coming from.

I was not expecting "It blew up from the toilet when I tried to flush." From inside the bathroom to outside, around the trailer and pulling the black tank dump valve in about 0.2s. Bawoosh! The force of the blast coming out pushed the RhinoFlex out to full extension of the slinky! (Here's where I give thanks to having a Rhino. I don't think a cheapo hose would have held up to that pressure.) Now I look over and realize the x-hose's valve is sitting at a 45, instead of fully shut.

Ah, so that's what happened. Somebody touched the valve, turning it on, and it filled my black water tank. After disconnecting the hose I headed back inside and was able to confirm with the wife that it was, indeed the toilet that threw the geyser. She was trying to determine where the water might be coming from and had opened the valve to see in the tank. As soon as the toilet valve was opened that freed the pressure by forcing the water up and into the bathroom.

So after a very disgusting, but very through cleaning of the whole trailer. (Thankfully we have disinfectant as part of cleaning arsenal) we managed to remove any sign of the water. During the cleaning, I was able to determine that the water dripping on the outside of the trailer was coming from the wheel wells, where the bathroom sits, and not from the underbelly, where the black tank sits. Since we have an enclosed underbelly, I wasn't able to see the tank itself unfortunately.

All cleaning done, we got the trailer put back together, I throughly scrubbed and then finished cooking a now cold dinner, and we ate outside. After dinner, showers (in the campground's facilities) and getting the kids off to bed, I was able to stop and think a bit about what happened.

Aside from the possible water damage, I'm concerned about 2 other things:

1) Where was the water coming from? I assume it was being forced out from between the tank and the toilet but not having seen the bathroom pre-flush-geyser I don't know. I might have a ruptured black tank, but the fact that it was leaking from the outer edge of the wheel wells instead of the enclosed underbelly gives me hope that I'm fine.

2) Why was the system under pressure? If I understand RV plumbing correctly, the water should have had an escape route via the vent in the roof. I checked the roof this morning, but didn't see any sign of the water being up there. Why didn't the water come up and pour out of the vent?

Being a holiday weekend, my dealer was closed, but you can bet that I'll be calling and booking into the Service Department first thing tomorrow morning.

So there's my "I never thought it could happen to me" story. Hopefully my experiences help save some of you out there from the same fate.

[Kaadk]

Oh, and yes, the ideas for a variety of mods are already forming for ways this could have been prevented. Stay tuned!

[rana]

Ya know I saw that title and the whole time the little mouse cursor was heading for it I heard that little voice "don't do it don't do it". I just never listen!! One of these days I'll learn my lesson (but I'm not holding my breath)

Thanks for the tip though. Little inconsequential things can sure reek havoc sometimes.

[Evereddie]

You are correct on the vent pipe should be where the water should go. Maybe a little leaking from the toilet but it should have come out the roof vent. Mine did when I goofed.

[BigJohnD]

We almost had an oops like that in 2010. I was doing the old flushing procedure, wife was inside cleaning. She hollered that the toilet was gurgling. At the same time I heard the vent stack gurgling. One of those oh crap, visualize what's fixing to happen, remember what you were supposed to be doing moments. Just in time, I pulled the dump valve. I had gotten distracted and went off doing something in the shop. That is the only, and last time that happened. Now, I refuse to get distracted, and become one with the poop tank cleaning.

[SKnight]

It could have been simple as the water was up to the top of the vent, in fact could it have been just starting to flow out of the vent?

Water has an actual weight of .447PSI for every foot of rise. That .5PSI (Easy math.) translated into roughly 4PSI times the 1.5" vent pipe, or seven pounds of water, between the floor and roof, depending how high above the toilet valve it was. Basically, at least a gallon of water would have gushed up on release. I don't know how much hit your floor but that's reasonable math to me.

As for how it leaked into the underbelly, those type of seals and connections aren't meant to hold pressure. It could have been a seep that won't return unless something like this happens again. But that's guessing, best let the dealer check that one.

I'd be more concerned over how/who flipped the valve.

[Witch Doctor]

The water might have started to go up the vent pipe, but when you open the toilet seal that gave the water the least path of residents and came down and emptied by gravity and the geyser happened in the head. I doubt if you damaged anything. Just made a big mess. If you would have ruptured the black tank it would have filled your underbelly and you wouldn't have realized it until your belly sagged enough to rip.

[Kaadk]

Originally Posted by SKnight

It could have been simple as the water was up to the top of the vent, in fact could it have been just starting to flow out of the vent?

Water has an actual weight of .447PSI for every foot of rise. That .5PSI (Easy math.) translated into roughly 4PSI times the 1.5" vent pipe, or seven pounds of water, between the floor and roof, depending how high above the toilet valve it was. Basically, at least a gallon of water would have gushed up on release. I don't know how much hit your floor but that's reasonable math to me.

I thought of that, but the wife said it 'hit the ceiling' and when I had looked there was about 1.5" depth of water in the sink, and about 3/4" depth in the tub. Still possible with a vent full of water, but rather coincidental that she'd manage to hit the flush just as water was near the top of the stack. I figure the more likely cause is that something (TP?) jammed the vent tube as it was filling, allowing the water to become pressurized. Eventually that back pressure would blow whatever was blocking the tube clear, possibly sending my vent cover flying and a geyser on my roof, but that would have taken a while and it is possible the DW flushed prior to that occurring.

Originally Posted by SKnight

I'd be more concerned over how/who flipped the valve.

I have my suspicions it's related to me telling my 4-year old no, he can't play with his water guns and no, Daddy wasn't going to go get him water. DW mentioned he was on the other side of the camper and this is coupled with my neighbour mentioning that my son was on that side of the trailer trying to suck up the water my neighbour was emptying from his coolers with his water gun.

Of course this all occurred while I was in the trailer doing prep work for dinner that night (cutting the vegetables for the chicken stir-fry) and I was never told about it until after the incident. If I had known he was over there I might have gone to check what he was doing and possibly found the valve pre-issue.

But I can't blame him, he doesn't know what the sewer flush is. Most likely he just saw a hose and tried to pull it out to get water. Really, I place the blame on myself. I should have known better than to leave the hose hooked up.

[SKnight]

Oh wow, yeah it was under pressure then. Definitely worth investigating how it ended up pressurized.

[RhoZeta]

Originally Posted by SKnight

Oh wow, yeah it was under pressure then. Definitely worth investigating how it ended up pressurized.

Yes indeed, I would be investigating this as well. Just hoping it was a wad of TP and some "material" blocking the vent. Good luck with it!

[Timex]

Originally Posted by BigJohnD

We almost had an oops like that in 2010. I was doing the old flushing procedure, wife was inside cleaning. She hollered that the toilet was gurgling. At the same time I heard the vent stack gurgling. One of those oh crap, visualize what's fixing to happen, remember what you were supposed to be doing moments. Just in time, I pulled the dump valve. I had gotten distracted and went off doing something in the shop. That is the only, and last time that happened. Now, I refuse to get distracted, and become one with the poop tank cleaning.

What an interesting choice of words!

[VinceU]

Originally Posted by Kaadk

Oh, and yes, the ideas for a variety of mods are already forming for ways this could have been prevented. Stay tuned!

I can understand how the toilet flange leaked right at the floor. Its a gravity flow joint to below, not a pressure fitting. I can understand how it never reached the vent, it would require about 7-8 psi to get that high, would likely relieve other places first. That vent is only for gases.

Can't understand why the Rhino was open to the tank, don't you normally keep that closed?

[vinmaker]

SO how may gallons do you think got into your camper? And was it all contained within the tub area or did it get onto the wood subfloor?

[Mary Ellen]

Crazy/cute story about the determination of a 4-year-old! He was going to get some water for his water guns, come heck or HIGH WATER!

Ugh. So sorry this happened to you. What an awful cleanup job.

[BamaBob]

OK so this is a practical application of that warning sticker that says "do not operate turboflush with black tank closed"...sorry it had to be you

So, if your tank was already flushed (thank goodness!!) what probably occured was water was flowing in and ambiant air was being vented out the roof. At some point the tank became full and water pressure slowly was filling the roof vent. Since water is heavier than air, the tank probably pressurized (distended) as the path of least resistance to the incoming water.

We would have to know the tensile strength of the black tank (seals, seams, and material) before we could speculate what would happen had you not caught the water when you did. SKnight's math on Water PSI would come into play as well so @ .45 PSI going up the vent AND up to the seal on your toilet. Once the toilet seal "filled" the only way "Up" would be the vent.

Sooooo long story short, your DW essentially pushed the plunger on a water land mine when she "flushed" the toilet, pressure from black tank+water backed up to seal+ who knows how much PSI from the tank and vent shot the water up from the toilet and hit the ceiling.

If I were the tech at your RV service center I would want to check - just to be sure - that all the seams and seals on the black tank are intact and not damaged in any way.

[Kaadk]

Originally Posted by VinceU

I can understand how the toilet flange leaked right at the floor. Its a gravity flow joint to below, not a pressure fitting. I can understand how it never reached the vent, it would require about 7-8 psi to get that high, would likely relieve other places first. That vent is only for gases.

Can't understand why the Rhino was open to the tank, don't you normally keep that closed?

Yep, the Rhino was closed to the tank... Until I pulled the valve to dump the tank because I knew it was under pressure.

[Kaadk]

Originally Posted by HSVBamaBob

OK so this is a practical application of that warning sticker that says "do not operate turboflush with black tank closed"...sorry it had to be you

So, if your tank was already flushed (thank goodness!!) what probably occured was water was flowing in and ambiant air was being vented out the roof. At some point the tank became full and water pressure slowly was filling the roof vent. Since water is heavier than air, the tank probably pressurized (distended) as the path of least resistance to the incoming water.

We would have to know the tensile strength of the black tank (seals, seams, and material) before we could speculate what would happen had you not caught the water when you did. SKnight's math on Water PSI would come into play as well so @ .45 PSI going up the vent AND up to the seal on your toilet. Once the toilet seal "filled" the only way "Up" would be the vent.

Sooooo long story short, your DW essentially pushed the plunger on a water land mine when she "flushed" the toilet, pressure from black tank+water backed up to seal+ who knows how much PSI from the tank and vent shot the water up from the toilet and hit the ceiling.

If I were the tech at your RV service center I would want to check - just to be sure - that all the seams and seals on the black tank are intact and not damaged in any way.

Yep, I have it on my to-do to get ahold of them and have that checked. That's my biggest fear, that I might have not ruptured, but did possibly bulge and therefore weaken the tank.

In the future, I'm thinking about borrowing a mod from your book Bob. I'm thinking about getting one of those water leak alarms and hooking it up to a couple of probes stuck to the top of the tank. I figure 110 DB should let me know my tanks are full. I haven't worked out the particulars of that design yet though, like how to prevent false alarms when you flush and the water splashes, etc...

[Kuba]

As they say
..."if there is no pictures-it didn't happen"
LoL j/k

[Kaadk]

I wish I did get pics, I'd have been able to give them to the dealer to help his diagnosis.

But unfortunately, taking pictures is not exactly the first thing on your mind when dealing with a trailer full of 'pooh water' as the kids were calling it.

[BamaBob]

Originally Posted by Kuba

As they say
..."if there is no pictures-it didn't happen"
LoL j/k

Sorry beat ya to it Kuba

It happened and here is the photos...
http://www.forestriverforums.com/for...tml#post669705