Holding tank bucket tests 2018 21BHS

[Gary M]

I just finished all the plumbing with re-directing my shower drain from the black to the gray tank, and decided to do the bucket test to confirm holding tank quantities. Here's the results I got...

Black tank: 30 gallons (advertised as 32 gallons)
Gray tank: 18 gallons (advertised as 25 gallons)
FW tank: 18 gallons (advertised as 26 gallons)

In conclusion, My black tank seems close enough to what it's suppose to be, but my gray tank is 7 gallons less than its suppose to be. I'm assuming its due to the vent pipe issue others have had. I'm wondering if anyone has attempted to access the vent pipe from the top side of the tank to cut it shorter, vs lowering the tank from the bottom of the trailer. This would be a much easier approach for those of us with underbellies if it is possible to do.
The freshwater tank being 8 gallons less than its suppose to be is no shocker to me after seeing how badly it sags between the 2 support braces. I'll probably have new braces fabricated to fix that one, and maybe even upgrade to a larger tank while I'm at it.

I've missed enough camping weekends this season due to repairs already, so this is something i would probably tackle this winter. Just want to hear others experience, inputs on the tank vent issue, and how they dealt wiith it. Thanks!

[charliem]

Gray tank: 18 gallons (advertised as 25 gallons)

................... but my gray tank is 7 gallons less than its suppose to be. I'm assuming its due to the vent pipe issue others have had. I'm wondering if anyone has attempted to access the vent pipe from the top side of the tank to cut it shorter, vs lowering the tank from the bottom of the trailer.

Shower into the wrong tank and vent problem too? I don't want to ask what else they could have screwed up. In models prior to yours the shower teed into the gray vent so the vent pipe couldn't be pulled up. For yours it depends on how the gray vent connects to the tank. If it goes straight in without any other fittings it might be possible. For further LL tank expertise I refer you to GaryM 

[Gary M]

Shower into the wrong tank and vent problem too? I don't want to ask what else they could have screwed up. In models prior to yours the shower teed into the gray vent so the vent pipe couldn't be pulled up. For yours it depends on how the gray vent connects to the tank. If it goes straight in without any other fittings it might be possible. For further LL tank expertise I refer you to GaryM  [/size]

Thanks Charlie, and that makes a lot of sense about the vent T's. My gray vent runs up the wall that is just forward of the bunks, and has nothing else teed into it. The kitchen sink drain passes right by it and goes into the top of the tank under the bunk. I'm thinking that since I have nothing teed, this job will be easier doing it from the top. I'll just have to reseal the vent on the roof once I'm done with some dicor. Looks like another winter project, so for now I can just dump my GW wherever while boondocking. This winter I'll also be looking into getting a bigger FW tank and solving the support brace issue.

We just finished up a 4 day trip with all the kids, and barely filled the BW tank at all, now that the shower drain goes to the right place! So I'm happy with the BW tank capacity.

[tbwrench]

 I haven't done it yet, but I've considered the problem of the sagging freshwater tank. The solution I've come up with is to get a piece of 1" x 1" angle aluminum and just world that onto the bottom of each support bracket. That should nearly double the width of the support bracket, plus the 1" perpendicular part to add strength.