Forum Discussion

SJ-Chris's avatar
SJ-Chris
Explorer II
Feb 12, 2022

Black waste tank connection question...

Glue the plumbing to the waste tank, or use a removable rubber coupling??


Recently, I had an issue that caused my black waste tank on my 2015 Majestic 28a to be partly disassembled (the piping from the tank itself to the waste hose hookup including the blade valve). My black valve wasn't working correctly also so I decided to replace the black blade valve.

So as I was working with this section of piping I noticed that the pipe joint that connects to the black waste tank itself was not physically connected/glued and simply slid in and out of the black waste tank inlet pipe. Specifically, it wasn't ABS glued together to be joined in a way that I would assume most plumbing to be joined/connected. It is possible there was a rubber union joint with hose clamps on each end to make for a leak-free connection. But I thought it was strange that it wasn't physically glued to be joined in a permanent/secure manner (which kind of surprised me).

My question: Should the sewer line from the black waste tank to the valve and dumping hose connection be all glued together to the black waste tank itself? Or should there be a rubber coupling connecting the waste plumbing to the black waste tank? (perhaps in case something needs to be changed in the future???).

I do think that gluing it all together as one piece makes sense from a leak-free perspective. But before I do that I just wanted to make sure I wasn't missing something. Because once glued to the black waste tank it can't easily be undone and additional repairs in the future would be VERY hard.

Note: The piping from the black waste tank to the valve (which is probably about 1.5-2 feet) consists almost entirely of slight bends and elbow type pieces, so if repairs were needed in the future it would probably require the entire section be rebuilt because there is no exposed straight piping that would allow for cuts and then rejoining with replacement parts. Hope that all makes sense.

-Chris
Class C
  • SJ-Chris's avatar
    SJ-Chris
    Explorer II
    Feb 14, 2022
    Added a couple more clamps just for good measure.



    While I was under there, I replaced the black blade valve which was jammed (...after getting to it, I saw it was just some toilet paper that was easily removed, but since I had the new blade valve I decided to just change it.



    There's one thing I would do differently...the 3" rubber coupling that I used was 4 inches long. This actually pushed the whole valve/drain assembly over by about 2 inches. I have since found that they make these couplings in sizes less than 4 inches. So if I replace the other one I will probably use one of these instead since it isn't as long...

    https://www.amazon.com/Valterra-F02-2103-Flexible-Coupler-3/dp/B00PHNCU30/ref=asc_df_B00PHNCU30/?tag=hyprod-20&linkCode=df0&hvadid=312089957955&hvpos=&hvnetw=g&hvrand=15711510602455972828&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032145&hvtargid=pla-571372074181&psc=1

    Did a small water leak test and so far so good.

    Happy Camping!
    -Chris
  • SJ-Chris's avatar
    SJ-Chris
    Explorer II
    Feb 13, 2022
    IAMICHABOD wrote:
    Is your second 28a the same way?


    RV1 = The RV black tank that I'm fixing because it came back with a patch and it failed on a trip.
    RV2 - My other identical RV I can use for reference.

    I am fortunate to have two identical RVs (2015 Majestic 28a units). When something is not working on one, I can go and look at the other. Convenient. Well, for this issue, I did look at the other RV but (until now) I couldn't really figure out what they did to connect the black tank to the drain pipe. I could see one clasp (kinda), but that didn't really make sense to me. Here is a picture of RV2 that currently is "fine" and giving me no problems:



    Now that I've taken apart the bad connection/patch on the other RV (RV1) and I can see that the pipe slides into the receiving pipe on the tank, I can understand how it is connected on RV2 is done. What they did on RV2 is they simply slid the drain pipe into the black tank receptor connection and then they put a clasp around it to tighten it. Well, I can tell you that the small piece that is part of the black tank is plastic, but it is kind of a thin plastic that is somewhat pliable. However, at the end of the day it is a plastic to plastic connection with a clasp that doesn't seem like a good idea at all. I can see what looks like some sort of flex-seal spray or something sprayed around the connection/clasp (probably because it was leaking!). It doesn't leak now, but now that I know a much better (hopefully) way to connect it I will fix RV2 to connect like my new connection on RV1. Here is the patch I did on RV1:



    I might even put one more clasp on each end just to reinforce the connection. I haven't water tested it yet but that will be my next step (...I'm adding a Tornado tank flush too as long as I'm working around the black tank).

    Happy Camping!
    Chris
  • Sjm9911's avatar
    Sjm9911
    Explorer
    Feb 13, 2022
    Fernco fittings are common in household waste/drain lines. I think it will last way longer then a few years. The clamps shouldn't loosen up easily eaither, I have 2 holding on a 4 inch pipe on my tounge, and a fence post on my rear bumper. So far, they haven't loosened. Good luck with the repair.
  • valhalla360's avatar
    valhalla360
    Navigator
    Feb 13, 2022
    Never seen a rubber coupling used.

    Maybe the rental place have a lot of issues with careless people hitting stumps and such with the plumbing, so it makes sense for them but it's really not a great solution. The hose clamp shown is only good for a few years before it dry rots. A properly glued and supported PVC setup should be good for a couple decades or more if you don't hit it on a stump.
  • ScottG's avatar
    ScottG
    Nomad
    Feb 13, 2022
    Yes, that is how it's designed to work. The polyethylene tank has a molded in nipple coming off it and a rubber connector like that is what's used to connect it to the plumbing.
    So, good solid fix!
  • SJ-Chris's avatar
    SJ-Chris
    Explorer II
    Feb 13, 2022
    After much searching (they were out at Ace Hardware and Home Depot), I found a 3" rubber coupling at Lowes that I thought had a chance of working.



    I got back to the RV and loosened the clamps as much as possible and after some effort I was able to get it around the pipe coming off the black waste tank. I already knew that it would fit on the drain pipe going to the valve as I was able to bring that with me to the store. Looks like I have my solution. I have 2 more clamps so I will install one more on each end of the connections and I think I should be good. I'll water test it to be sure but this must be how it was designed to be connected (rather than ABS glue which would make it a permanent connection).

    I'll try to get a picture of the final connection to upload here.

    -Chris
  • IAMICHABOD's avatar
    IAMICHABOD
    Explorer II
    Feb 12, 2022
    There was a video a while back with a couple that had a bad experience with their Cruise America rental,one of the problems they had was a leak from the black tank,he crawled under the RV and found that the pipe had pulled out of the tank,there was a rubber coupling with hose clamps on each end that had come loose. She called Cruise America and was told just to tighten it up as best they could and bring it to the nearest dealer and they would fix it.

    When they got there they wanted a new unit which I think they got,it was explained to them that it happened sometimes and reason for the rubber coupling was if it was damaged in any way it could be replaced quickly and the unit would be back on the road with little down time,thus still making money.

    Maybe one of the other members could slide under and look,It may have not been replaced when it was refurbed.

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