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

valhalla360
Navigator
Jul 13, 2020
C Schomer wrote:
BAD BAD IDEA! It's not just common sense and I can't recite them but there are strict codes to keep sewage and gray water isolated and handled properly and to protect your health and potable water! Back flow preventers, vacuum breakers, one inch minimum air gaps between any drain and water that even comes from a potable source and on and on, just for starters. Connecting black and gray would turn the entire drain system into a black system and that would be one step closer to contaminating the potable water. Sewage in sinks and showers, so close to the potable water system, not to mention sewage smell every time there was a dry trap. Unimaginable... don't do that to yourself! Craig

Please share these strict codes with us.

Black and Gray are already connected...there is no backflow prevention just a simple blade valve.

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?
C_Schomer
Explorer
Jul 13, 2020
BAD BAD IDEA! It's not just common sense and I can't recite them but there are strict codes to keep sewage and gray water isolated and handled properly and to protect your health and potable water! Back flow preventers, vacuum breakers, one inch minimum air gaps between any drain and water that even comes from a potable source and on and on, just for starters. Connecting black and gray would turn the entire drain system into a black system and that would be one step closer to contaminating the potable water. Sewage in sinks and showers, so close to the potable water system, not to mention sewage smell every time there was a dry trap. Unimaginable... don't do that to yourself! Craig
valhalla360
Navigator
Jul 13, 2020
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.
Lynnmor
Explorer
Jul 13, 2020
You may want something like this.
schlep1967
Nomad
Jul 13, 2020
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.
jdc1
Explorer II
Jul 13, 2020
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.
schlep1967
Nomad
Jul 13, 2020
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.
gkainz
Explorer
Jul 13, 2020
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.
schlep1967
Nomad
Jul 13, 2020
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.

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