Casita SD17 Nature's Head Composting Toilet

[Bob Penn]

It was my intent and goal well before I purchased my new Casita SD17 to replace the factory toilet with a Nature's Head Composting toilet. After a false and unsatisfactory start, I finally made the install which I consider clean and neat. I thought I would share pictures of the install in case there were others who may be interested in the same project.


Removing the factory installed toilet was fairly simple. I must warn you that the factory uses what seems like gallons of silicone rubber sealant to install the factory toilet and black tank. Unlike home toilets that use a soft wax ring to seal the toilet to the floor, the factory uses silicone rubber sealant instead. Understandable considering the shock and vibration the toilet is subjected to during transit. It took me several hours to clean the silicone off of the fiberglass (FG) floor around the opening to the black tank.


Next I cut 1" thick foam rubber matting which I purchased at Home Depot (Fig 1). I secured this to both sides of the fiberglass toilet deck. I used 3M permanent double sided tape to secure the mat to the fiberglass. The top of the mat also received the 3M tape (red in Fig 1). I did not use the top tape in the end as the bolts securing the floor to the fiberglass made the floor very secure.


The factory installed toilet water supply line was plugged and secured to the back wall of the wet bath (Fig 4). It is there should future owners prefer to have a standard toilet in the RV.


The new floor was cut from a 24"x30" piece of 3/8" Baltic birch which I purchased from the local Woodcraft store (Fig 3). I added cleats to provide additional horizontal position support around the toilet in the new floor. A pattern of the new floor was made by cutting cardboard to fit the area. The new floor was finished with 5 coats high gloss polyurethane. The Nature's Head mounting "L" brackets were then secured to the new floor. The green tape on the FG was to mark the center line of the black tank opening for cutting a 4-1/2 opening in the new floor.


I used the factory toilet mounting bolts (Fig 2) reversed through the original holes in the fiberglass with wing nuts inside the black tank to hold the floor down. My goal in this project was not to add any new holes to the FG shell. I plugged the black tank opening with a 4" knock-out test cap from Home Depot (cost - 48 cents - see photo)


Once the floor was securely fastened, I used GE Advanced White silicone sealant (Fig 4) to fill the space between the new floor and the FG walls of the wet bath.


With the new floor complete, the next task was to connect 12 VDC from the Nature's Head exhaust fan to the wet bath light fixture just above the black tank vent. I drilled a 9/64 " hole in the bottom of the light fixture (Fig 5 & Fig 6) and ran the Nature's Head exhaust fan power cord up through the hole into the light fixture. I soldered the positive (red stripped) lead to the hot side of the light fixture on/off switch. That was easy. I could not get solder to stick to any of the negative connections. To fix this problem, I used a 1" inch hose clamp around the base of the led light socket and clamped the negative lead (white stripped) between the hose clamp and the LED socket base.


To protect and secure the Nature's Head power cable, I used Legrand Cordmate C10 cord channel cut to 35” (Fig 7). Legrand Cordmate has a self stick adhesive which I attached to the wet bath wall. The Nature's Head power cord was routed through this channel.


Finally, I sliced a 1-1/2x1-1/2x1-1/4 PVC “T” lengthwise to fit over the black tank vent pipe (Fig 8). I secured the “T” using hose clamps (Fig 9). I don't remember what size they were as I cut off the excess of the hose clamps once they were properly fitted. I inserted a 2” piece of 1-1/4” PVC pipe as a fitting to receive the flexible hose provided by Nature's Head for the exhaust of the toilet. Once the “T” was firmly in place, I drilled a 1-1/4 hole in the black tank vent pipe.


I plugged the power into the Nature's Head Toilet. I connected the flexible exhaust hose to both the Nature's Head exhaust port and to the black tank vent and the installation was complete (Fig 10 & Fig 11).


If anyone is interested in more detail will be happy to respond via private message to any questions you may have.

[Travel Hawk]

I must say you did a very professional and clean install. But by having a casita spirit dlx myself and by knowing the geometry of the bathroom floor, i have to ask is the toilet seat too high for sitting comfortably on it? Thanks for sharing with many details of your install.

[Rzrbrn]

Very interested din your install. Very professionally looking install. Would you please follow up after you have used it a bit. I am wondering about flys and other insects. Also smell, but this is not all that important.

[Stephen_Albers]

I also installed a NH toilet. I also converted the black tank to freshwater.

[Bob Penn]

Originally Posted by Travel Hawk

I must say you did a very professional and clean install. But by having a casita spirit dlx myself and by knowing the geometry of the bathroom floor, i have to ask is the toilet seat too high for sitting comfortably on it? Thanks for sharing with many details of your install.

I am 6'8" tall, so I would suspect that my height would represent the extreme. If I sit up ram rod straight. My head touches to top of the bath. I do not know of anyone who sits straight when doing their business. So I do not see head room as a problem. What does present something of a problem is the floor. It was even a challenge with the factory installed toilet. With the shower pan so deep, it is my opinion that a foot stool of some type is needed though I have managed without the foot stool so far. I am considering several options. One is a collapsible tote and the other is the collapsible stool of which I have both. The totes I bought at Costco and the collapsible stool I found on Amazon. Both items serve multiple purposes and require minimal storage space. The collapsible tote is probably the best solution in my opinion.

[Bob Penn]

Originally Posted by Rzrbrn

Very interested din your install. Very professionally looking install. Would you please follow up after you have used it a bit. I am wondering about flys and other insects. Also smell, but this is not all that important.

Let me address the smell first. I used the NH for some time without the exhaust fan and vent connected. I personally did not detect any smells. But it is also important that I be honest with you. My smeller is not fully functional at my age.


After a period of non-use, the tiny flies did show up. I have a small battery operated Black & Decker vac that sucked them up. I don't think most people have a problem with the flies and insects. I have read many reviews and watched a ton of YouTube videos. Flies and insects are rarely mentioned. I also considered using "insect spray" to kill them. I do not see where the insect spray would negatively impact the composting process. It is my plan to microwave the coconut coir in the future prior to use to kill any insect eggs that may be in the composting material. The other possibility is to bake the composting material in the oven for 20 minutes.

[Bob Penn]

Originally Posted by Stephen_Albers

I also installed a NH toilet. I also converted the black tank to freshwater.

I have never used the black tank. How did you convert the black tank to fresh water use?

[Rzrbrn]

I have researched this subject now and again and just when I think I will take the plunge...er... install a composting toilet I come across a negative mention of these two issues, and I walk away from the notion. It certainly is compelling, however.

[CASITA BANANA]

After a full year of living with an AirHead composter, I can report never having problems with odor or insects. Period. I you do, you're doing something wrong.

It's one of the best mods I've done on my 16SD. What a relief (pun intended) not to have to search for dump sites or to be limited dry camping by using up precious water for a conventional toilet, or by prematurely filling up the black water tank.

They've been used successfully on boats for years.

Clean up is easy and not as gross as you would imagine. And, sorry, I don't think anyone who's never had one can honestly critique them.

[Timber Wolf]

Originally Posted by Bob Penn

I have never used the black tank. How did you convert the black tank to fresh water use?

I think, and hope, he meant grey water use.

[Bob Penn]

Originally Posted by Timber Wolf

I think, and hope, he meant grey water use.

My black tank is still virgin. So I suppose it could be converted to use for fresh water. My drinking water will be from a Berkey water filter. Before using the black tank, I need to clean the construction debris out of it first.


I had/have no plans for using the black tank.


Your comment about converting it to a gray water tank is a very good point though.

[tmaken2157]

Well done, that's a great post. I had a casita, now I have a surveyor, but my heart is with the eggs. Anyway don't hold it against me. I put the NH in mine and have used the coco coir. Can you tell me how much to add to the NH, I hit the right load once and went all summer, but now is a bit too much and the crank gets cranky

[Coyaba Clan]

Bob, what an impressive mod, so clean and professional. I to am a huge fan of the composting toilet option. My approach required a different model toilet. I wanted to see if the urine bottle could be mitigated so we went with a “Compoosting” toilet from the UK. (No it’s not a typo;-)

As well as the same “solids” results the unit has a powered mixing approach a interior urine bottle an attachable charcoal air filter option and a broader deeper urine catcher (wife approved).

The interior urine bottle was the key. In short we removed it and used the space to drill a hole thru the toilet allowing access to the black tank. We then ran a hose from the urine spigot thru the hole into the black tank and sealed it in place, There’s an inline shutoff valve with enough tubing to create a p-trap effect.

I wish I had thought of your power mod. I may have to upgrade to it. We just installed an interior 12v rechargeable battery. It powers the micro fan & power mixer for about 10 days before needing a recharge.

I don’t think we get the same volume usage as NH. We have to empty the pot about once a week. But not having to dump a urine bottle seems to be a fair trade off.

I hope Casita takes note of these kinds of mods. The convenience and capacity options/improvements could be a heck of an move forward for them.

Cheers - Glenn

[burnauk]

Originally Posted by Bob Penn

My black tank is still virgin. So I suppose it could be converted to use for fresh water. My drinking water will be from a Berkey water filter. Before using the black tank, I need to clean the construction debris out of it first.


I had/have no plans for using the black tank.


Your comment about converting it to a gray water tank is a very good point though.

The idea of converting the black tank is very interesting. I have a 16' Liberty model, and could easily convert the black tank to a "gray tank" for the kitchen, and the bathroom sink, should I choose to install a composting toilet.

That would make for a "four season" gray tank, after some work on the exterior plumbing, reducing the length of the dump line to only a couple of inches below the floor, then the blade valve. I wonder if the valve would be leak free mounted horizontally....

[CASITA BANANA]

The blackwater tank may not be non-toxic. The kind of plastic it's made of isn't designed for potable water because it didn't have to be.

I took my blackwater tank out and put down a heavy aluminum diamond plate for stability under the composter.

[Bob Penn]

Originally Posted by Coyaba Clan

Bob, what an impressive mod, so clean and professional. I to am a huge fan of the composting toilet option. My approach required a different model toilet. I wanted to see if the urine bottle could be mitigated so we went with a “Compoosting” toilet from the UK. (No it’s not a typo;-)

Cheers - Glenn

I only recently became aware of the "Compoosting Toilet" (hereafter referred to as "CT") from the UK. There is a YouTube video by Foxes Afloat which details their removal of a cassette toilet and replacing it with the CT you mentioned on their narrowboat. The link to that video is:

https://www.youtube.com/watch?v=4qgHnfB5cFw

I was extremely impressed with the CT. I love the idea of pushing a button and the toilet does the mixing of the solids for you as well as an indicator light to tell you when your liquid's bottle is full. Emptying the solids "bucket" is also much simpler on the CT than with the NH. With the NH, you have to almost completely disassemble the entire toilet to empty the solid's container which is the base of the unit. This is my biggest criticism of the NH. With the CT, you only raise the lid and remove the solids bucket.

There is a saying that you get what you pay for. In this case, that saying is true. The CT from the UK is approximately about 25 percent more than the price of the NH. Add to that, Trans Atlantic shipping costs. If you add any of their accessories, that will add even more. They have some very creative and excellent accessories. A link to their site is provided below.

Another consideration of the CT is that it requires additional power for the agitator in addition to the fan. The NH uses a tiny fan and the power draw for the fan is very small.

I am not sure that my solution for accessing the trailer's power would work for the CT. You would have to determine the current draw for the agitator on the CT before using the wet bath light as a power source.

If cost is not a factor, I would definitely go with the CT! With my change to lithium batteries and solar, power is not a factor. I did not compare the weight of the two units, but it appears that the NH may be heavier. There was no information on their site as to the weight of the CT unit or the power required for operation. Mounting of the CT is definitely easier.

For those interested, Compoost's website: https://compoosttoilets.com

[Rzrbrn]

Thank you very much for the CT connection. I went to their website. They say in the write up that a replacement 12v motor can be purchased but I do not see it in the list of products sold. My thought is to buy replacement parts at the same time as the toilet because the company may not be around when the replacement parts are needed. It appears to be very well built and useable. This has real possibilities.

The video shows the CT being used to replace a cassette toilet, and has electricity available. The install would be a bit more difficult to replace an RV toilet and to find a way to get an electrical connection to it. But this is perhaps being nitpicking. Very nice indeed.

From the company website:
We can also supply a spares/service pack to include:-
Motor (plug and play)
Urine sensor (plug and play)
Fan

[Rzrbrn]

Bob, your skills are impressive. How did you make the contour of the birch floor so perfectly match the curving contour of the Casita floor/wall? When I owned my Casita I tried to match the curve and it did not match up anywhere close to what you have accomplished.

[Rzrbrn]

Originally Posted by CASITA BANANA

After a full year of living with an AirHead composter, I can report never having problems with odor or insects. Period. I you do, you're doing something wrong.

It's one of the best mods I've done on my 16SD. What a relief (pun intended) not to have to search for dump sites or to be limited dry camping by using up precious water for a conventional toilet, or by prematurely filling up the black water tank.

They've been used successfully on boats for years.

Clean up is easy and not as gross as you would imagine. And, sorry, I don't think anyone who's never had one can honestly critique them.

These are the sites that have kept me from buying a composting toilet:
https://www.thefitrv.com/rv-tips/the...osting-toilet/
and this: https://drivinvibin.com/2020/08/17/r...sting-toilets/

Others say good things about composting toilets, of course, including Bob. I suppose I will just have to encounter someone on the road that will let me inspect the thing so I can see for myself. Too difficult to rip out the old and too expensive to make a mistake that might be hard to undo.

[Bob Penn]

Originally Posted by Rzrbrn

Bob, your skills are impressive. How did you make the contour of the birch floor so perfectly match the curving contour of the Casita floor/wall? When I owned my Casita I tried to match the curve and it did not match up anywhere close to what you have accomplished.

Henry, actually the final solution was quite simple.

After removing the factory installed toilet, there was a huge amount of silicone rubber compound they used in place of the normal wax ring to seal the toilet to the floor. It took me about 3 hours to carefully carve away and peel away all of that silicone rubber. Everything after that was much easier.
I purchased a package of foam floor pads similar to the following link at Home Depot.
https://www.homedepot.com/p/Ottomans...lack/302692940
I bought was a 4-pak. I cut 2 wide strips from one foam pad to go on each side of the raised section of the toilet mounting area. The thickness of the pad and the height of the raised toilet ring were very close to the same height. I used industrial double stick tape to fasten the foam padding to each side of the toilet mount area. Note the red tape in one of the photos. I originally planned that both the top and bottom of the pads would be secured. In the end, the extra mounting tape was not needed. However I did not remove it. I suspect the additional 2 layers of the mounting tape made up for a perfect fit.

I cut 3/8 inch Baltic birch plywood to fit the area. I removed the original toilet mounting bolts. I cut a hole just slightly larger than the black tank hole in the new floor I drilled holes in the wood floor to match the original mounting holes. Then I reversed the original mounting bolts and used them to secure the new floor to the toilet area. The new flooring fit completely flat. No additional effort was required. I used a white silicone caulking compound used in bathrooms to seal the edges of the floor around the floor perimeter. The caulk added even more stability to the installation.

A 68 cent 4 inch plastic plug from the HD plumbing department fit perfectly in the black tank access and sealed the black tank from any water or debris getting into the tank.
If I were to do it over, I would add a facing strip at the front to completely seal in the floor.
A note about my modifications I make to the trailer. I try to make every mod in a way that the trailer can be easily returned to its original configuration. You will note that the water supply to the old toilet was not removed. It is simply plugged and fastened to the back wall of the wet bath available to the next owner who wants the old toilet instead.
Pull the mounting bolts, the black tank plug and the floor out and all that is needed is a flushing toilet. Reverse the bolts and add a tube of silicone rubber sealant in place of a wax ring, connect up the water supply and you are once again back to the trailer's original wet bath.