My kids got a used RV and on their maiden trip discovered the black tank dump plumbing leaks. Appears to have one or more cracks in the plumbing from the tank to the dump valve. They tried to patch it with flexseal to get them through the weekend but didn't stop the stinky drips.Taking a quick look at the dump plumbing, it appears to be a series of 3 or 4 elbows from tank to dump valve with little to no pipe sections that could be cut and new elbows glued up to replace the cracked section(s).How does the first fitting secure into the black tank? I didn't notice any flexible type seal or joint and a hose clamp, but again, was just a quick look, not a close inspection. My fear is that this first fitting is glued into the tank outlet?Thanks for any suggestions! I intend to manage this repair and give my son-in-law instructions from a safe distance :)

They can do it any number of ways. Mine has the valve right at the tank. On thing to consider is the use of a fernco coupling (google it). If he can cut right before the leak at the end of an elbow and use a fernco to attach to the new piece he should be fine.

schlep1967 wrote:They can do it any number of ways. Mine has the valve right at the tank. On thing to consider is the use of a fernco coupling (google it). If he can cut right before the leak at the end of an elbow and use a fernco to attach to the new piece he should be fine.Thanks - will look into that. My rig also has cable pull dump valves right at the tanks. I was thinking about suggesting that improvement for him, as well as combining black and grey plumbing into 1 dump valve and connector - his rig has separate dump hose connectors and separate dump valves for black and grey tanks, with the generator installed between them. For simplicity of repairs, I think we're going to stick with just replacing the leaking parts.

gkainz wrote:schlep1967 wrote:They can do it any number of ways. Mine has the valve right at the tank. On thing to consider is the use of a fernco coupling (google it). If he can cut right before the leak at the end of an elbow and use a fernco to attach to the new piece he should be fine.Thanks - will look into that. My rig also has cable pull dump valves right at the tanks. I was thinking about suggesting that improvement for him, as well as combining black and grey plumbing into 1 dump valve and connector - his rig has separate dump hose connectors and separate dump valves for black and grey tanks, with the generator installed between them. For simplicity of repairs, I think we're going to stick with just replacing the leaking parts.Plumbing the two dump hose connectors together is fine but you want to keep separate valves. Otherwise you essentially only have one big combined tank. Better separate so he can drain black and then flush the hose with grey.

If you're trying to get the glued ABS sections apart, in the construction trades we use a small grinder with a diamond blade. We cut the overlapping section just deep enough to touch the inserted part. Make 5-6 cuts. Then use a small (1/2") chisel to remove the overlapped ABS fitting. Sand down the left over particles/glue, then start glueing the new parts in place. Be sure to use glue on both male and female parts. It's a pain working on your back, but it's a lot cheaper than having someone do something this simple.

jdc1 wrote:If you're trying to get the glues ABS sections apart, in the construction trades we use a small grinder with a diamond blade. We cut the overlapping section just deep enough to touch the inserted part. Make 5-6 cuts. Then use a small (1/2") chisel to remove the overlapped ABS fitting. Sand down the lefy over particles, then start glueing the new parts in place. Be sure to use glue on both male and female parts.For the price of new fittings, I ain't working that hard. I had to replace about half of my system last week after a blow-out tore of the end piece. Cost including a container of the proper glue ($7) and tape for the underbelly ($6) was right at $30.Now if you can't find the correct replacement parts, different story. Time to do the work.

Black tank dump plumbing replacement? | Good Sam Community

ol_Bombero-JC
Explorer
Jul 23, 2020
valhalla360 wrote:
schlep1967 wrote:
Plumbing the two dump hose connectors together is fine but you want to keep separate valves. Otherwise you essentially only have one big combined tank. Better separate so he can drain black and then flush the hose with grey.

Honestly, if I was rebuilding from scratch, I would lean towards a single valve.

As long as you use plenty of water when flushing, it shouldn't be a big issue if they all drain together.

But if you don't fully utilize the kitchen gray tank, you effectively get more storage for the black & shower as they will back up into the kitchen gray tank.

valhalla360 - first thought for you...."we" all know the mfgrs will cut corners to save a buck at every opportunity. *If* your "one tank" plan is/was a good one - the mfgrs would be doing it already...:S

However - back to those codes you want. Code sections will vary from jurisdictions, however - Here's one to consider....

Depending on the location - whether city, county, state, or feds... if *spilled or leaked* - your "concoction" of black & grey is is a bio-hazard. Not so with "only" grey.

*Maybe* depending on the amount, and/or if you're quick with your own clean-up - or do same on "the sly" you may get away with it......if not, you may/will be responsible for paying for a licensed remediation outfit for clean-up!

As a former Haz-Mat team member, I can vouch for it being a reality.
Plenty of your fellow camper/neighbors will "rat you out"! The "authority having jurisdiction" may have very limited "leniency" options (if any).

BTW - It AIN'T cheap !!....:(

~
schlep1967
Nomad
Jul 21, 2020
valhalla360 wrote:
Alan_Hepburn wrote:

The issue isn't the water from a shower backing up - it's the other direction: the shower pan is the low point in the system, so if your single waste tank gets full the only place for it to go is into your shower pan, bringing with it whatever is in that single waste tank. I'm sure your wife would not appreciate it if she's taking a shower when that happens...

I usually look before stepping into the shower (as does my wife)...maybe it's just us.

But even if it is backing up into the gray tank for the shower, while it's not hermetically isolated, it's going to be shower water coming back up...and it's still going to be nasty either way.

Still not seeing how it's going to jump to the fresh water system.

The concern is black water coming up into the shower while you are taking a shower.
valhalla360
Navigator
Jul 16, 2020
Alan_Hepburn wrote:

The issue isn't the water from a shower backing up - it's the other direction: the shower pan is the low point in the system, so if your single waste tank gets full the only place for it to go is into your shower pan, bringing with it whatever is in that single waste tank. I'm sure your wife would not appreciate it if she's taking a shower when that happens...

I usually look before stepping into the shower (as does my wife)...maybe it's just us.

But even if it is backing up into the gray tank for the shower, while it's not hermetically isolated, it's going to be shower water coming back up...and it's still going to be nasty either way.

Still not seeing how it's going to jump to the fresh water system.
Alan_Hepburn
Explorer
Jul 15, 2020
valhalla360 wrote:

If you overfill your shower, it's shower water you are standing in (unless you've put a recirculating pump from the gray tank in).

The issue isn't the water from a shower backing up - it's the other direction: the shower pan is the low point in the system, so if your single waste tank gets full the only place for it to go is into your shower pan, bringing with it whatever is in that single waste tank. I'm sure your wife would not appreciate it if she's taking a shower when that happens...
gkainz
Explorer
Jul 14, 2020
Let me clarify ... by separate systems, I mean this trailer has a pipe exiting the black tank to a dump valve and dump hose connector - completely and totally isolated from the grey system.

Then it has another, completely separate and isolated pipe exiting the grey tank to a different, completely separate dump valve and completely separate dump hose connector ...

and in between the 2 sewer hose connectors is the generator exhaust pipe.

Connect the hose to the black tank, pull the dump valve, and dump the black tank. Disconnect the sewer hose and move to the gray tank connector, pull THAT valve and dump the gray tank.

I had discussions with him about putting new dump valves next to both tanks and plumbing into a single Y and connector. We both agreed to just fix what’s broken.

I've done enough plumbing, household up to center pivot irrigation systems that I'm comfortable with joints, fittings, pipes, glueing, bonding, etc that I can get through that part of the repair. What I wasn't familiar with is the actual coupling to the black tank. I see on Amazon and elsewhere that they sell repair parts and kits that include a flange for a tank which is what I'm hoping to see.

Lynnmor up above linked to a drill to resize the fitting to the original dimensions ... brilliant! :)

And thanks as well to jdc1 for tips on getting the glued stub (if that's what we're facing) out of the connector.

Thanks for the input - appreciate it!
mchero
Explorer
Jul 14, 2020
One valve for both tanks?
NOT!
After dumping your hose wont be flushed out.
As stated above, possible sewage backing up thru shower!
Not a smart move!
valhalla360
Navigator
Jul 14, 2020
4x4van wrote:
On the contrary. There are several reasons to keep them separate. First is, as has already been mentioned, the possibility of black tank smells coming through the sink and shower traps while driving. However, the biggest is that if you happen to overfill the grey, it comes up in the shower. It's one thing to have grey water in the shower, it's another entirely to have sewage in the shower.:(

If you have traps, smells won't come up. (and gray water often smells worse than black)

If you overfill your shower, it's shower water you are standing in (unless you've put a recirculating pump from the gray tank in).

So still waiting on a good reason.
4x4van
Explorer III
Jul 14, 2020
valhalla360 wrote:

Only reason to keep them separate is if you are somewhere that only allows gray water dumping. At one time it was considered acceptable to dump gray water on the ground but not black water. That was many years ago...now it all needs to go into a dump station and I've yet to find one that has separate drains for Black vs Gray. Who cares if it's all a Black water tank?

On the contrary. There are several reasons to keep them separate. First is, as has already been mentioned, the possibility of black tank smells coming through the sink and shower traps while driving. However, the biggest is that if you happen to overfill the grey, it comes up in the shower. It's one thing to have grey water in the shower, it's another entirely to have sewage in the shower.:(
houstonstroker
Explorer
Jul 14, 2020
If you want to patch the cracks I have had good results with Plasti Mend on my black water tank. It chemically melts the tank and makes a new layer.
wa8yxm
Explorer III
Jul 13, 2020
Flex seal is great stuff but .. not for that

GOOP works better

But ... You might want professional help with that job Pipes are replaceable. Just make 200% sure tanks are empty before cutting into the pipe.

pipe is easily found multiple places not exclusive to RV Though the valves you will need to get from RV source.