Black tank flush overfill

[sprintnut]

Hooked city water to black tank flush and got distracted. Toilet was full but not overflowing. Water was running out belly of camper. No water on bathroom floor. Pulled black water drain valve. (It was already flushed out.) Let camper set until water quit running out of underbelly.
Now what? What is broke? How can I check it? Any input welcomed & appreciated.
Russ

[cummins2014]

dougrainer wrote:

cummins2014 wrote:

dougrainer wrote:
OK, one thing that can happen when you do this, it can BREAK the 3 inch down tube from the black tank. The Pressure involved when you do this is tremendous. 45 psi or more has filled the black tank and now the tank has expanded(swollen) and popped either the 3 inch down tube loose or the 1.5 inch vent tube loose. We know this because instead of water coming out the roof vent and overflowing on the roof it came out the bottom from the top of the tank. Because the tank broke open at the tank which is a good thing instead of out the roof vent. NOW, if you do NOT fix the problem on top the tank, you will have black tank odor migrating into the lower bottom cavity because it is NOT sealed now. The RVIA standard for both Gray and Black is to hold water when overfilled. With Black we fill until the water is just below the toilet ball valve and on Gray with water coming into the shower or tub. Also, unless you access and clean out the top of the tank and the underbelly and insulation, you will now have a musty smell all the time. Both inside and out. Doug

IMO that’s not the best way to tell if the black tank is full , for us is an air bubble forms when flushing , and that’s full enough for me . As far as letting it start filling the shower floor that may work for you , but the one time it happened to my wife while showering , she wasn’t that thrilled to be standing in the waste water . We know pretty much our usage on the gray tanks , and every three days or so I just pull the handles for a few seconds , and save enough when I do the black tank to flush the pipes a bit better , then I just empty all three, and start over .

Did you NOT read what I posted? I was posting how a Service shop TESTS the Tanks on a PDI, NOT HOW to tell when tanks are full. Doug

Yes , and your wording could of said what you just replied or been more clear . Go back , and edit that would help . Thanks .

[Cummins12V98]

dougrainer wrote:
OK, one thing that can happen when you do this, it can BREAK the 3 inch down tube from the black tank. The Pressure involved when you do this is tremendous. 45 psi or more has filled the black tank and now the tank has expanded(swollen) and popped either the 3 inch down tube loose or the 1.5 inch vent tube loose. We know this because instead of water coming out the roof vent and overflowing on the roof it came out the bottom from the top of the tank. Because the tank broke open at the tank which is a good thing instead of out the roof vent. NOW, if you do NOT fix the problem on top the tank, you will have black tank odor migrating into the lower bottom cavity because it is NOT sealed now. The RVIA standard for both Gray and Black is to hold water when overfilled. With Black we fill until the water is just below the toilet ball valve and on Gray with water coming into the shower or tub. Also, unless you access and clean out the top of the tank and the underbelly and insulation, you will now have a musty smell all the time. Both inside and out. Doug

How do you know this? There is a roof vent there for a reason, I don't see how pressure can be added when there is a vent.

[Cummins12V98]

time2roll wrote:
Step away like a boss. Nothing happened.

How do you know???

[way2roll]

nickthehunter wrote:
Why do people not leave their black tank valve open when flushing the tank? Valve open, tank won't overfill, why would I want to risk a disaster?

Because it's not only the force of the water from the flush to "wash" debris from the sides of the tank, it's the physics involved to use a 1/2 or 3/4 full tank's rush of water to flush all that debris out the hose. I repeat this process several times until I get clear water. The trick, as the op found out, is not to walk away and let it overfill. It's only a disaster if that happens.

[dougrainer]

cummins2014 wrote:

dougrainer wrote:
OK, one thing that can happen when you do this, it can BREAK the 3 inch down tube from the black tank. The Pressure involved when you do this is tremendous. 45 psi or more has filled the black tank and now the tank has expanded(swollen) and popped either the 3 inch down tube loose or the 1.5 inch vent tube loose. We know this because instead of water coming out the roof vent and overflowing on the roof it came out the bottom from the top of the tank. Because the tank broke open at the tank which is a good thing instead of out the roof vent. NOW, if you do NOT fix the problem on top the tank, you will have black tank odor migrating into the lower bottom cavity because it is NOT sealed now. The RVIA standard for both Gray and Black is to hold water when overfilled. With Black we fill until the water is just below the toilet ball valve and on Gray with water coming into the shower or tub. Also, unless you access and clean out the top of the tank and the underbelly and insulation, you will now have a musty smell all the time. Both inside and out. Doug

IMO that’s not the best way to tell if the black tank is full , for us is an air bubble forms when flushing , and that’s full enough for me . As far as letting it start filling the shower floor that may work for you , but the one time it happened to my wife while showering , she wasn’t that thrilled to be standing in the waste water . We know pretty much our usage on the gray tanks , and every three days or so I just pull the handles for a few seconds , and save enough when I do the black tank to flush the pipes a bit better , then I just empty all three, and start over .

Did you NOT read what I posted? I was posting how a Service shop TESTS the Tanks on a PDI, NOT HOW to tell when tanks are full. Doug

[cummins2014]

dougrainer wrote:
OK, one thing that can happen when you do this, it can BREAK the 3 inch down tube from the black tank. The Pressure involved when you do this is tremendous. 45 psi or more has filled the black tank and now the tank has expanded(swollen) and popped either the 3 inch down tube loose or the 1.5 inch vent tube loose. We know this because instead of water coming out the roof vent and overflowing on the roof it came out the bottom from the top of the tank. Because the tank broke open at the tank which is a good thing instead of out the roof vent. NOW, if you do NOT fix the problem on top the tank, you will have black tank odor migrating into the lower bottom cavity because it is NOT sealed now. The RVIA standard for both Gray and Black is to hold water when overfilled. With Black we fill until the water is just below the toilet ball valve and on Gray with water coming into the shower or tub. Also, unless you access and clean out the top of the tank and the underbelly and insulation, you will now have a musty smell all the time. Both inside and out. Doug

IMO that’s not the best way to tell if the black tank is full , for us is an air bubble forms when flushing , and that’s full enough for me . As far as letting it start filling the shower floor that may work for you , but the one time it happened to my wife while showering , she wasn’t that thrilled to be standing in the waste water . We know pretty much our usage on the gray tanks , and every three days or so I just pull the handles for a few seconds , and save enough when I do the black tank to flush the pipes a bit better , then I just empty all three, and start over .

[Lwiddis]

I think Cummins has made the right call and I believe you need a major cleaning sooner rather than later.

[time2roll]

nickthehunter wrote:
Why do people not leave their black tank valve open when flushing the tank? Valve open, tank won't overfill, why would I want to risk a disaster?

A lot more debris comes out with the rush of the filled tank draining again. The spray alone will not move a heavy wad on the bottom.

I find the sensors work fine to determine ~75% full and pull the lever. Takes real focus to avoid getting distracted. With some experience a timer could be set.

[nickthehunter]

Why do people not leave their black tank valve open when flushing the tank? Valve open, tank won't overfill, why would I want to risk a disaster?

[dougrainer]

OK, one thing that can happen when you do this, it can BREAK the 3 inch down tube from the black tank. The Pressure involved when you do this is tremendous. 45 psi or more has filled the black tank and now the tank has expanded(swollen) and popped either the 3 inch down tube loose or the 1.5 inch vent tube loose. We know this because instead of water coming out the roof vent and overflowing on the roof it came out the bottom from the top of the tank. Because the tank broke open at the tank which is a good thing instead of out the roof vent. NOW, if you do NOT fix the problem on top the tank, you will have black tank odor migrating into the lower bottom cavity because it is NOT sealed now. The RVIA standard for both Gray and Black is to hold water when overfilled. With Black we fill until the water is just below the toilet ball valve and on Gray with water coming into the shower or tub. Also, unless you access and clean out the top of the tank and the underbelly and insulation, you will now have a musty smell all the time. Both inside and out. Doug

[dougrainer]

One thing to do is get a mechanical Lawn sprinkler timer. THAT will help stop this from happening.
Also, this helps when people use a Y hose connection with shut offs. IF the cutoff seeps/leaks, then it will slowly fill the black tank. Doug

https://www.amazon.com/Orbit-62034-Mechanical-Watering-Timer/dp/B006FLGHGE/ref=asc_df_B006FLGHGE/?ta...

The type Y

https://www.amazon.com/Splitter-Shut-Off-Irrigation-Watering-Suitable/dp/B07SZMFXPH/ref=asc_df_B07SZ...

[TXiceman]

You are lucky it did not rupture the seam on the black tank.

Ken

[time2roll]

Step away like a boss. Nothing happened.

[Cummins12V98]

You just filled your RV with SEWAGE. Once the tank is full it fills the vent pipe and once that is full it boils over the top of the pipe to run back down the outside of the pipe and out the underbelly.

Look on the roof your vent pipe is not sealed it just vents under the rooftop vent. Your tank fitting did NOT leak. If it was not tight you would have POO JUICE constantly weeping traveling down the bumpy roads with POO in the tank.

To avoid this EXACT problem as it is VERY easy to get distracted I set the timer on my phone for 10 minutes with a LOUD Dog Bark when I close my tank valves and hav the flush system activated.

Just wait for the SMELL once the heat cooks the POO. If this happens you may want to file an Insurance claim.

[ford_truck_guy]

My guess is your black tank has a "slip fit" on the top with gasket..

HOPEFULLY - You just need to drop the underbelly and allow EVERYTHING to completely dry out.. Possibly replace insulation if there is any... Once insulation is removed, give the underbelly a good spray of disinfectant before closing up.
This happened to me but it was not from a hose left turned on.. I Used to ( ROOKIE MISTAKE ) keep my black tank flush hose hooked to the trailer with the shut off valve closed the night before leaving. my valve failed and slowly filled the tank to the point of overfilling and spillage into the underbelly.