Composting toilet installation in a T@B 400

Denny16 · February 2020

You could, but how fast have you filled the grey tank? The more valves you install, the more issues you can have with disconnected lines. I would keep it simpl and go for number 5, seems like the quickest and best option.
cheers

gspdx · February 2020

@fishergary- You have a 320, right? Not sure how all the tanks on the 320 are configured. I think trying to plumb the kitchen sink to the black tank in a 400 would be a major problem. The only place I can think you could run the drain line would be under the floor and then that line would be below the entire black tank.

I could drain the bathroom sink into the black tank but that wouldn't gain much since we don't put much water through that sink. But every gallon helps!

The yellow tank idea sounds promising. Maybe the bathroom sink and yellow tank?

fishergary · February 2020

@gspdx - Yes I have a 320. I agree - I don't think there is a good way to connect the kitchen sink to the black tank.

Thanks for the comments everyone. I will update as the project moves along and post a write up of the installation. I also have a lot of other mods planned - I'm basically trying to make the ultimate 320 Boondock...

gspdx · March 2020

OK - I am thinking too much about the black tank conversion even though I haven't installed the composting toilet yet. But I might try something like this when I get there:

Transfer pump from grey to black tank.

To do this I need a way to get grey water out of the grey tank and pumped into the black tank. I was thinking about a hand pump for a basic test.

I was thinking I could cut into the ABS vent pipe from the black tank and install a tee with a fitting where I can attach a water line. I could then run the water line out through the outside shower. See the factory tour video of the Tab400 here to find the vent pipe. Start at 3:33 on the video:https://www.youtube.com/watch?v=lBDgzCYjxZM

Next I was thinking just add a cover with a hose fitting to the waste outlet for the grey and black tanks: https://www.amazon.com/Valterra-T1020-1VP-Waste-Capped-Carded/dp/B0006N5RV8/ref=sr_1_2?dchild=1&keywords=valterra+cover&qid=1585065800&sr=8-2

A small hand transfer pump could then be connected from one to the other and water pumped into the black tank: https://www.amazon.com/Koehler-Enterprises-RA990-Multi-Use-Transfer/dp/B0181EDCZ6/ref=sr_1_6?dchild=1&keywords=hand+pump&qid=1585066209&sr=8-6

Not a perfect solution but relatively cheap and would test the idea. If that goes well a more permanent solution with an electric pump could be figured out.

Michael49 · April 2020

Great thread. We are thinking of installing a composting toilet in our 400. Anyone here use Nature's Head instead of the Airhead?

gspdx said:

OK - I am thinking too much about the black tank conversion even though I haven't installed the composting toilet yet. But I might try something like this when I get there:

Transfer pump from grey to black tank.

I have been following van conversions for a while and one feature that many vans have is a valve on the bottom of their grey tanks to simply dump right below the van- they can usually open this valve from a switch inside the van - I'd love to have this on our 400.

We use only biodegradable products. I've never used a dump station for our grey water. I usually periodically empty our grey water tank with a bucket and just dump it in the woods. If I take an outdoor shower, wash my dishes outdoors or brush my teeth outdoors, there is no issue with that, but dumping grey water from a tank onto the ground is often seen as taboo - it makes no sense! - it the same thing!!

Denny16 · April 2020

The TaB400 has a separate valve for dumping the grey water tank, in addition to the valve that dumps the black tank. The normal sequence is to first dump the black tank (at an official dump station of course), then flush the black tank with an external water connection to the black tank, then dump the grey tank to flush out the dump hose. You can buy a garden hose adapter for the tank connection (shared by both tanks) to dump your grey water some where else, like watering plants...

cheers

Michael49 · April 2020

Denny16 said:

... You can buy a garden hose adapter for the tank connection (shared by both tanks) to dump your grey water some where else, like watering plants...
cheers

I like the garden hose attachment idea! A release valve directly below grey tank that is operable from inside the Tab would be nice though.

Michael49 · July 2020

Old thread, new question.

I've decided to install a C-head composting toilet in my 400. I've chosen this model as it requires no ventilation or power.

I would like to leave as much of the water supply intact as possible in case I decide to reinstall the OEM toilet at some point.

Can I simply cap the waterline where it enters the hose to the toilet?

Denny16 · July 2020

Sure, do not see why not, or add a valve to it.
cheers

Michael49 · July 2020

Alright guys. This is more of a plumbing question then a tab question. I capped the PVC pipe with a plastic threaded end cap. When I pressurize the system it leaks. Is this because I didn’t use PVC cement? I was trying to avoid this because I wanted The ability to remove the endcap at some point in the future. Would Teflon tape work or do I need to use PVC cement?

fishergary · July 2020

I would use Teflon paste ideally, but Teflon tape should work. Definitely don’t use PVC cement or it will be permanent.

Michael49 · July 2020

fishergary said:

I would use Teflon paste ideally, but Teflon tape should work. Definitely don’t use PVC cement or it will be permanent.

That's what I thought - thanks.

Michael49 · July 2020

Does anyone know how these bolts are removed?

fishergary · July 2020

I didn’t see a good way to remove them. I just cut them off with a grinder.

Michael49 · July 2020

fishergary said:

I didn’t see a good way to remove them. I just cut them off with a grinder.

That’s what I was afraid of.

I wanted to leave them intact in case we decided to remount the factory toilet for resale.

I wonder if I remove some of the wax if I can simply remove the flange or if the flange is cemented to the floor in addition to the bolts that I already removed. Or is the flange threaded, does anyone know?

Sharon_is_SAM · July 2020

Maybe email Austin in repairs@nucamprv.com. You probably won’t hear back until Monday or so.

Can’t you plug it like @Haloo did at the beginning of this thread?

Michael49 · July 2020

Got them out after removing some of the wax and a bit of finessing.

@Sharon_is_SAM I have a plug, that’s Wasn’t the problem. You can see how far those bolts were sticking up. If I built a three-quarter inch plywood Frame/mount for the composting toilet those bolts would extend up into the mount. So glad I was able to remove them!

Michael49 · July 2020

Michael49 · July 2020

Made a cardboard template, then made my mounting board for the composting toilet!

The mounting board is birch. I would like to paint this with something white and reasonably water resistant, any recommendations?

Still trying to decide how to mount this. I don’t want to permanently screw it into the floor. I will definitely caulk around it which will hold it somewhat, thinking about Something Simple like VHB tape.

The toilet itself will also have a mount which can be easily removed, possibly wing bolts as the toilet will need to be removed periodically.

Sharon_is_SAM · July 2020

Will a self leveling epoxy adhere to wood? The kind you use to cover a cement floor.

Denny16 · July 2020

Not very well. You can use a adhesive caulk, known as 3M 5200 that will bond the ply down, and keep it there. Seal the ply all way round with a ply sealer, than prime and paint with a bathroom type enamel paint. Then adhere the ply in place with the 5200. After 24 hrs, the ply is not going to come up or off.
cheers

Michael49 · August 2020

Finished up the composting toilet Installation today. This is the C-head brand. I ended up using Peel and stick vinyl flooring over the Birch mount. I then used bolts up through the mount, through the composting toilet to hold it in place. I then used large fender washers and wing bolts. The composting toilet does not need to be removed to be emptied (there is an inner bucket that is removed for solid waste and a jug for urine). The only time the toilet itself needs to be removed is if you want to clean the toilet but having the wing nuts makes that easy to do.
This particular toilet also does not require any external ventilation or power for a fan.
We will be using it quite a bit over the next several months, will see how we like it soon enough, but especially in the Covid era its nice not to worry about having to empty a black tank.

jrhamel · August 2020

@Michael49 How did you end up adhering the plywood to the plastic floor?

Michael49 · August 2020

jrhamel said:

@Michael49 How did you end up adhering the plywood to the plastic floor?

Double sided 3M VHB tape.

krsmes · December 2020

Michael49 said:

fishergary said:

I didn’t see a good way to remove them. I just cut them off with a grinder.

That’s what I was afraid of.

I wanted to leave them intact in case we decided to remount the factory toilet for resale.

I wonder if I remove some of the wax if I can simply remove the flange or if the flange is cemented to the floor in addition to the bolts that I already removed. Or is the flange threaded, does anyone know?

Late response to an old thread but for future reference to those that have this question — I just went through this mod myself and yes the entire flange is removable - it unscrews with some brute force (applied via a screwdriver and hammer turning it an eighth of an inch at a time until it is loose enough to grab and turn by hand). Saves an inch in height when installing the (taller) dry toilet and avoids having to add a compensating board around it.

thetuningspoon · April 2022

Has anyone tried a compost toilet modification on the 2021 or newer 320 with the cassette toilet? I really like the new 320s but the compost toilet is an absolute must for me (I live in a tiny house and have experience with the AirHead already).

I can't tell what things would look like underneath if you were to remove the cassette toilet. Also, it looks like the little sink takes up a lot of valuable space, so it would be nice to be able to remove that too (why do we need a bathroom sink in such a small trailer when there's one right outside the door in the kitchen??). But since the faucet doubles as the shower head, that could be opening a can of worms.

Slackers · April 2022

This modification is more straight-forward in an older (2019 and older) 320. The older model's sink and shower are separate from the toilet. Also the toilet is not a cassette style.

IMO unless one is spending many nights off-grid and not traveling where dump stations are readily available, I don't think the cost-benefit ratio is favorable for a retrofit.

Denny16 · April 2022

That said, once removed, the cassette toilet will leave an unfinished wall behind the sink and cassette toilet, and an opening in the side to the cassette door. This would not be a trivial modification to make.
Cheers

thetuningspoon · April 2022

That's what I was afraid of. I built my own house so I'm not afraid to get my hands dirty, but I don't love the idea of tearing apart a brand new $30,000 camper without any guarantee of success. I guess I will have to look for used.

It looks to me like 2020 was actually the last year with the regular toilet, and also the first year with the white walls, so I think that's the model I'll look for.

Slackers · April 2022

I believe some of the 2020 320s have toilets with integrated sinks which span the width of the bathroom. You may want to avoid these too because you'll have to patch behind your replacement toilet. Just saying to be careful when shopping.

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Composting toilet installation in a T@B 400

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