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Black tank woes

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Always an attention grabber I know!

Our 99 Rexaire toilet started leaning to one side a little then started sinking into the floor.

Today I pulled up the carpet and as expected the floor is rotten around the base of the toilet about 12 x 16. It is a 16 year old coach so that's fair enough.

I flushed and emptied the black tank and removed the toilet but the flange and the pipe down to the tank appear to have separated on one side. There's a fillet of some kind of adhesive that I can get my fingers under.

I'm hoping I can reattach the pipe to the tank.

Any advice/opinion?

I searched the archives and a few likely adhesives came up but the one referred to on Amazon is now "no longer available".

DW would like a working bathroom!




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The needed adhesive will depend upon what the tank is made of. The rotten floor probably means that the toilet has leaked either around the base of possibly a small leak of the flush water. Make sure that you fix that if it has not been or the problem will return.

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Thanks Kirk

The seal between the toilet and flange was completely rotted.

We went to South Coast RV in Chula Vista CA and their tech ran us thru the likely causes and fixes. He recommended silicon caulk around the tank/pipe junction which appears to be what was there already. To make the floor fix easier we bought a new floor flange and a length of 3" black PVC pipe just so we can set the new flange flush with the new floor.

I'll post the results hopefully tomorrow


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Be sure to get all of the old sealant off if silicone because it will not stick to the old, cured sealant. It would be good to use the same thing that was used in the manufacturer process. It is fairly common for the pipe from the black tank to the toilet to actually extend slightly into the tank and for some small amount movement to be allowed for.

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If you can get to the piping under the floor then I would say to check that the pipe is sealed at the tank area. If that is good then replace the floor, and locate the hole for the flange. Cut the pipe off that is coming out of the tank so there is about 3" or more sticking out.Or above a elbow if neaded. it will depend on the situation at hand. Now assemble the flange and pipe but leave the pipe about an inch short.

You then need to lubricate the 3" pipe with dielectric grease which is just silicone. Not silicone sealant.

Now use a 3" fernco fitting to join both pieces of pipe.

Search the internet to see what a frenco fitting is. It will seal the 3" pipe but leave a little bit of flexibility in the system.


if you are going the silicone thing I would clean all the old off and use goop. It is much better than silicone. I have installed black water fittings with goop. Goop is available at Walmart for about 4 bucks a tube.



Safe Travels, Vern

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I finally got the floor/toilet thing fixed if you are interested in the procedure I posted it to our blog http://banbrv.blogspot.com/

It turned out that the pipe into the black tank was good and I didn't need to get all fancy and replace the flange. I did remove the big glob of black silicone that was not adhered to much, then I cleaned everything and put a much thinner coat around the tank/gasket junction and the pipe/gasket junction.

"All's well that ends well" we hope. We have tested it over the last few days with no leaks or bad smells



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