Holding tank fittings

[TinyDoug]

Hi. I'm Doug, live in a very cold climate (high in the mountains), and am building a tiny house intended for year round living. I intend to install holding tanks in the heated space and can tolerate no leaks. What is the best way to attach incoming drain lines to the tanks to best insure that they do not leak? If I use grommets, can I glue fittings to them? Should I direct glue fittings to the tanks? BTW, I have a composting toilet, so only sinks and shower go into tanks.

Thank you.

[ajriding]

I dont know your exact plumbing plan, but yes glue is fine.
Maybe you can use rubber p-traps or rubber connections after you glue the fittings on. See Homedepot shelves. The rubber pipes flex plenty and are held on with hose clamps.

That said, I have done repairs and rigidly glued fiberglass holding tanks to pvc plastic pipes and driven a lot. No leaks. I used fiberglass epoxy in this case, which is more brittle than the plastic glue you will use on your ABS tanks, so I would not expect any issues on yours.

[TinyDoug]

Thank you all so much!! And BTW, it won't be a stationary installation. Tiny House on Wheels, which NM considers an RV. Although I will not abuse it like I do my offroad teardrop camper, I still will tow it.

[time2roll]

Need to post the tank material. Consider reviewing the tank manufacturer recommendations. May even come with the needed fittings.
For leak free be sure to install the pipes with no fitment stress and need to be well supported.

[opnspaces]

As Chris Bryant states the glue will not break. ABS glue is also incredible easy to work with. Just coat both surfaces and stick them together with a slight twist. Be quick though as ABS glue is a lot like super glue in that is cures fast.

You coat both pieces with glue and have a few seconds to carefully position the parts near each other. But once the parts touch you only have about a second or two to give them a slight twist to spread the glue and then it's solid.

Here's an example of the coupler Chris was referring to. Link

[ScottG]

For installs other than factory, there are glue-on ABS fittings and rubber, grommet-like fittings. Both work very well but the glue in type might be a little more forgiving of over filling.
Do not use glue with the rubber type.

[Chris_Bryant]

The solvent weld will not break- I would be tempted to put a no hub coupling in which is just a short rubber hose clamped over the outside of the two pipes. That said, the abs survives bouncing down the road, so a stationary installation shouldn’t be a problem.

[TinyDoug]

Chris Bryant wrote:
It depends on the tank material, most waste holding tanks are abs, and fittings are solvent welded. Polyethylene tank fittings are spin welded or use grommets. Wanting it to be leak free, I would be tempted to use metal.

Thank you. My tanks are ikon and alpha, ready made, and are, I believe, abs. There are no holes for drain fittings, and I will have to drill. My concern was that if I solvent weld, and things wiggle even slightly (pot holes anyone?) that there might be lateral/twisting forces on the joints and the weld would break. I've never worked with abs before (total amateur, but with no money hire pros, and no pros within 50 miles or more) and don't know how strong welded abs joins are.

I intend to waterproof (red guard) the compartment containing the tanks, but still don't want things to leak!

[Chris_Bryant]

It depends on the tank material, most waste holding tanks are abs, and fittings are solvent welded. Polyethylene tank fittings are spin welded or use grommets. Wanting it to be leak free, I would be tempted to use metal.

[BarneyS]

I believe most of the tanks used on RVs have the fittings spin welded on. I see no problem using gaskets if the tanks do not move as the sink and shower will have P traps to prevent odors from coming in as long as there is liquid in the traps.

Perhaps you can find a manufacturer that will add the fittings you need as long as you supply accurate drawings. Worth a try anyway.:) . Good luck.
Barney