Community Forums

Jay D. · 06-12-2021, 04:36 PM

Quote:

Originally Posted by n2zon

Yes. 5' of water pressure is more than 2' of water pressure. The diameter of the water column does not matter.

Submersible pumps can push water much higher than 20'. Some household submersible well pumps can be as deep as 400'. Sump pumps, by contrast, usually have lower limits (less than 30').

There are also self-priming non-submersible (and not jet) pumps. From a standpoint of physics, it's impossible to pull water up farther than 34' because you pull a vacuum in the line first. On a more practical level, self-priming pumps usually won't pull water up quite that far.

Jet pumps will push water up farther than self-priming pumps, but nowhere near as far as submersible pumps. They're limited to about 200'. (Ours is 130' deep.)

This is what i was getting at. pressure in the black tank during a clean out like the O/P can be caused by water filling up in to the vent and being forced out. its not necessarily a plugged vent tube ,but partly filled with water that causes the pressure and explosion.
nice conversation with you though.
Jay D.

rvgrandma · 06-12-2021, 08:29 PM

We had that happened. I was at the doctor's when my husband called in a panic 'the toilet exploded'. By the time I got home it was pretty well cleaned up but happened again a couple hours later - thankfully was clear water this time. Turned out we left the flush out hooked up to the faucet. The 'Y' we had on was leaking thus filling the tank. Now I don't leave it hooked up.

dpinvidic · 06-12-2021, 10:50 PM

So the OP said he tried city water a second time, and the black tank filled with water.
Sounds like two possible problems.
1. City water pressure is too high. Pump pressure is lower, city pressure may force its way past the flush valve.

2. He is hooking the tank flush to city water....unlikely mistake, but not completely unheard of.

Good call by those who pointed out that as the black tank gets past full, the water column continues up the vent pipe....just waiting to be released when the toilet is flushed

KanzKran · 06-13-2021, 05:20 AM

Quote:

Originally Posted by dpinvidic

Good call by those who pointed out that as the black tank gets past full, the water column continues up the vent pipe....just waiting to be released when the toilet is flushed

And since the vent is lower than the valve in the bottom of the bowl, potentially by a lot, there will be an air space as long as the valve doesn’t leak. With water up into the vent, there’s compressed air and water in that tank and especially the pipe to the bottom of the bowl, which would explain the ‘exploding’ part when the valve is opened.

Monkey Run · 06-13-2021, 11:42 AM

Interesting thread

!

At any rate, a friend picked up a new to him camper, and not being totally familiar with it, hooked the camp water up to the flush fitting. He did not realize his mistake until it blasted out the toilet and all over the inside of this almost new tagalong (and his girlfriend). The OP has most likely solved the poop pressure problem by now...

Dave Pelletier · 06-14-2021, 09:58 AM

Quote:

Originally Posted by Monkey Run

The OP has most likely solved the poop pressure problem by now...

I'm sure but it would be nice to know. I'm betting that he connected to the flush system instead of the domestic water inlet.

Dave

VanDiemen23 · 06-14-2021, 01:01 PM

I can't remember what caused it, but we had an RV converted to an instrumentation van for work.

Accidentally left the pump on overnight and it developed a leak somewhere - can't say where because we didn't troubleshoot it - just made sure we never left the pump on unless the toilet or sink was in use.

BUT - it completely filled the black tank overnight. it was completely full, and the toilet was right at the top. Luckily there had never been anything in it but pee, and a gallon of pee in 50 gallons of water is not a big deal. We got there just as the carpets got wet.

This was an Airbus and Rexall cut a lot of corners on that thing. The point is that depending on how the thing is plumbed the right combination of failures can produce this problem.

As far as building pressure - seems like insects or other debris in the stack would be the likely culprit. I'd start on the roof and snake it.

B RAD · 06-14-2021, 04:14 PM

OK, Just got back home and had no problems with black tank explosions or leaks for the rest of trip. Can’t believe I did it but to everyone who said I must have hooked the fresh water to the black water clean up, You were right! In my defense as feeble as it is, the city water hookup is just 4 inches above the black tank flush out inlet. They are both labeled and I have hooked them up correctly many times, this time OPPS!!!!!!!!!! AW ****!!!!

Dave Pelletier · 06-14-2021, 05:08 PM

Quote:

Originally Posted by B RAD

OK, Just got back home and had no problems with black tank explosions or leaks for the rest of trip. Can’t believe I did it but to everyone who said I must have hooked the fresh water to the black water clean up, You were right! In my defense as feeble as it is, the city water hookup is just 4 inches above the black tank flush out inlet. They are both labeled and I have hooked them up correctly many times, this time OPPS!!!!!!!!!! AW ****!!!!

Could happen to anybody; thanks for the update.

Dave

Bigd9 · 06-14-2021, 06:46 PM

Quote:

Originally Posted by B RAD

OK, Just got back home and had no problems with black tank explosions or leaks for the rest of trip. Can’t believe I did it but to everyone who said I must have hooked the fresh water to the black water clean up, You were right! In my defense as feeble as it is, the city water hookup is just 4 inches above the black tank flush out inlet. They are both labeled and I have hooked them up correctly many times, this time OPPS!!!!!!!!!! AW ****!!!!

Thanks for getting back to us!

LETMGROW · 06-15-2021, 06:23 AM

Quote:

Originally Posted by B RAD

OK, Just got back home and had no problems with black tank explosions or leaks for the rest of trip. Can’t believe I did it but to everyone who said I must have hooked the fresh water to the black water clean up, You were right! In my defense as feeble as it is, the city water hookup is just 4 inches above the black tank flush out inlet. They are both labeled and I have hooked them up correctly many times, this time OPPS!!!!!!!!!! AW ****!!!!

We learn by doing! I'd venture to say this won't happen again.

robertkathy · 06-18-2021, 10:29 AM

I drained my tank this morning and got side tracked and after closoing the drain valve forgot to turn the water to the tank cleaner off.
While taking a shower i heard t noise, ran out of the shower and outside still trying to get the bathrobe on made it to the drain just in time.
2 years fultiming never done that before