Black tank cracked...twice.

[bobbyg123]

Hi everyone. Haven't posted here in a while, so I hope this message finds you all well.

I've run into a confusing situation with the black tank(s) on my 2018 Jayco Eagle 5th wheel. Last Fall 2022, I discovered that I had a leaking black tank. After removing the underbelly, I noticed that the tank had cracked at the outlet joint. I wasn't able to successfully repair it, so I opted to purchase a new tank and have it replaced. I store my camper outside, and I figured that some residual water must have frozen and caused the tank to crack. Not a huge deal, other than the cost, so I had a local RV technician handle the repair.

Fast forward to this Fall. Just a few weeks ago, the same darn thing happened to the new tank in just about the same place. Another crack near the outlet joint. This time I know it wasn't a result of freezing temps, but I'm dumbfounded about what's causing it. The angulation of the tank stressing the exit pipe? The blank tank sagging when it gets full and straining the exit pipe? It's driving me crazy trying to figure this out. It's a 30G tank, and it's not *that full* following our weekends. Maybe 15-20G tops.

We use the camper to tailgate for college football in the Fall, and I utilize a mobile dump tank service to empty the tanks following the game weekends. I've used the service for years and years without issue. I've had a Jayfeather and a Keystone Bullet travel trailer that never experienced this issue.

Any ideas on what the problem could be? I've got the camper winterized now, but my technician is going to completely remove the underbelly in the Spring and try and deduce the problem.

[TCBear]

I vote for Plastic-Mend! Much cheaper than another tank swap.

Adding to what Jffnkrn mentioned, make sure to Google "RV dump stations/sites" such as Sanidumps and RVDumpSites. Also your municipal and county public works departments, which sometimes offer dump service at their sewage treatment facilities.

[Endricken]

Plastic-mend works well to repair ABS Black Tanks

[jffnkrn]

not sure where you are located in relation to an rv store, sales, service etc.
they usually have a dump station, a cost included i am sure. the other option is to find a close by rv park that will allow you to dump, of course with associated cost, another option is if you can reach your cleanout at the house, that would work or a truck stop or camp ground with dump station. All of most likely of course with an associated cost. Good Luck

[bobbyg123]

Thanks for the input. You guys are right. It has to be the mobile pump out service. Adds up too, as I discovered the most recent crack after the 1st pump out of the season. Game 1, didn't need the pump service. No problems. Game 2, also no problems. Pump out service provided and then the leak was discovered during the 3rd game weekend.

Well crud. The problem I have, other than the crack(s), is that there isn't a convenient alternative dump option. The site I store my camper on doesn't allow dumping into portable totes. I'll figure something out though.

Thanks everyone!

[TCBear]

I did some quick sleuthing on the InterTubes and at another forum (irv2.com), and think I can answer...

At one annual RV jamboree they have hundreds of vacuum pump-outs with no issues, so this is indeed an uncommon problem. But as Enblethen mentioned, the jamboree specifically warns people to manually block open the toilet flush valves. The roof vent may not suffice. The trucks also suck out subterranean cesspools and therefore can generate substantial vacuum to lift from depths. Some folks have reported tank damage from such service, and one guy reported damage to BOTH his wastewater tanks from a single service. Keeping the toilet flapper valve open and reducing vacuum on the truck can solve the problem. Some service techs were new and literally unfamiliar with the possibility of damage! A safer method is to gravity drain into a large, low bucket and have the tech insert his truck hose into the bucket, pulling from the bucket. More difficult, have the tech insert his hose into the end of your drain hose and suck from that. Or perhaps you could gravity drain into a large tote and have the tech pull from the tote, repeating that several times, closing and reopening the RV valve to help segregate that system from damage (or repeatedly removing the drain hose from the RV). Designed as a gravity drain system, RV wastewater systems aren't well suited to withstand either substantial pressure or vacuum.

[TCBear]

As for the repair, any chance you could slather epoxy, fiberglass resin or similar over the area rather than a second tank replacement? An initial thought for me was that some weight could have been placed on the drain outlet, causing damage where it connects to the tank. But the pipe's hanger would bear the brunt of that load, so I'd carefully check the hanger for evidence as well. Otherwise perhaps vacuum damage as others have mentioned. A unique and interesting scenario.

[ScottG]

Even the extra weight of the mobile vac equipment and rough handling could be a factor. I would avoid them in the future.

[jffnkrn]

i have never used a pump service, but I agree, the pump service may be the cause, if it isn't the suction it could possibly be teh downward pressure or strees put on the hose connection forcing extra upward force where the drain pipe is connected to the tank. another thing that makes you go HMMM

[enblethen]

Using a vacuum truck to empty holding tanks need to have an extra caution. Open the toilet valve and block open. The trucks vacuum sucks harder than the roof top vent system can handle.

[MFL]

We are just guessing, but agree with above as to mobile tank service.

Without a pic, it's hard to know if there is any other issue, such as lack of, or improper support for the tank and attached fittings.

In any case, a small tank should be able to handle the waste load if properly installed.

Jerry

[nickthehunter]

I would guess that the mobile dump tank service is the one thing that you are doing that 99% of other RV owner”s aren’t doing. For me, that would be my first likely suspect.
You are investing in looking at the design and mounting of the tank. But it doesn’t seem to be an issue a number of other owner’s are having. So I would ask myself “what am I doing differently?”