Composting Toilet - new to this!

So I'm about to embark on a few new ventures of my life for the very first time all at the same time! One is living off-grid. Another is becoming a mother! And finally, on top of handling my baby's waste differently to how anybody else I know does (everybody I know uses disposables), I'll be experimenting with what to do with contents of a compost toilet when the only property I own is a boat. I don't have any land to build the proper composting facilities I've been researching. So I'm not entirely sure what I'm thinking other than I just really don't want to full time deposit straight into the canal...

I'm looking for tips in other threads as well but thought I'd open my own discussion here for documenting my progress as I go & getting tips from anybody who might have advice.

I've been researching a lot and am pretty sure about going with a diverting system keeping liquid separate from solid. I'm not so worried about disposing of the urine. I'm thinking of just using a watering can and disposing daily on wild plants until I have some of my own (potted). It's the "humanure" solids that I'm struggling to plan for. I've seen something about using a "3 bucket system" or a "bucket to barrel" system, but I haven't come across people who've actually used this system to reassure me it works and won't fill up so fast that I don't have space or anywhere for it to finish (or even start) it's composting process. There is the possibility of family letting me use their land, but this isn't nearby and if bucket filling is fast, won't be convenient in any way...

Anyway, here goes nothing! All advice welcome.

I'll warn, especially with a baby, the buckets will fill up fast, and would suck to transport if you have to do it as often as I suspect you would.

Is it just you and baby? How many in the household? How are you anticipating you'll collect and store sawdust for the toilet setup?

I think doing this on a boat with no land would be challenging, but interested to see what insights others may have.

Margaux Knox wrote:Is it just you and baby? How many in the household? How are you anticipating you'll collect and store sawdust for the toilet setup?

It would be me, baby & daddy. I anticipate it will be tricky alright, but I'm not sure what other options we have. My hope is that I can find a rhythm or routine that would see the composting process start in the bins on board, but I'm not sure if that's really how it works. At least that could reduce the number of times we would have to transport. I'm also considering if I could hide a wheely bin somewhere in plain sight but this would be a public place and could be considered a hazard...

May I ask what kind of systems you have experience with? I'm confused about whether the bin composting system works if it's totally dry (no urine) or is a liquid necessary to keep the temperature up...

As for sawdust, I was actually considering collecting leaves in the autumn since they'll be easy to find and then buying a bag of peat moss or sawdust as a backup.

For a 3 barrelling system, can anybody recommend what kind of barrel would work best? Plastic, steel or wood?

OK here's what I am planning so far... this is mainly me thinking out loud and documenting so that I can come back to this.

The boat already has a bathroom. It's extremely small, but has a good working shower sink and toilet. The main problem with the room, besides the toilet flushing straight to the canal, is that the room has little ventilation. You can see that from the existing damage to the ceiling in that room. The only window doesn't open but there does appear to be a vent pipe already on top. I plan on leaving this toilet in tact for when things go wrong with this compost toilet! But also plan for this compost toilet to NOT go wrong! So I need this vent!

The compost toilet would be in the next room. This is because I really don't think having a shower in this room where I'm trying to keep the solids bucket dry would be a good idea. Moisture should be prevented! Having said that, in the wall just next to the existing bathroom where the new toilet will go, there is a window that opens! I need this window to help with ventilation from the shower! So I need the vent in the bathroom with shower for the compost toilet in the next room and I need the window above the compost toilet to help ventilate the shower in the other room! Sounds ridiculous but I think it might be solvable!

I plan on opening a hole at the top of the wall between the shower room and the compost toilet, where there will be an electric fan to pull the moisture from the bathroom into the compost toilet room... But only use it with the window wide open! I plan to also have a fan that ventilates the box where the compost toilet will be, to go up and pass through the wall to the shower room and up through the existing vent! That needs to be bug proof of course...

So far for all that I need:
- 2 fans, exhaust and ventilation fans ?? I'm not sure which.
- Some pipes for the air to flow from the compost toilet box
- Something to bug proof the vent...

Next, the containers...

From what I've researched so far, I hear the liquids are what causes the smell. So I definitely want to separate my liquids from my solids! Just for the comfort of being discreet (!!) I'm considering using a watering can as the urine container, but I would need one where the only open hole is through the spout we pour from. That's to keep it sealed and reduce the chance of smell. Not entirely sure how easy that will be to find but I'm sure there have to be some that have lids... Otherwise I'd have to find a way to seal it. I'm considering even using 2 of these... one under the liquid diverter which goes in front of the solids bucket/barrel, and another below a urinal attached to the wall... This is because I have my doubts that my partner will always sit down to do what he has to do!

- Liquid diverter
- Basic urinal on the wall
- 2 x lidded watering cans
- 2 x Flexible tubes to run from the urinals above into the watering cans
- Spray bottle of water & vinegar mix for spraying urinals after use

As for the solids, I'm researching everything there is to know about the 3 barrel system as it's the only thing I think I have space for that possibly won't require me to set up an actual outdoor aerobic humanure compost heap that would require a piece of land! Maybe someday when we return to land, if this system has worked we can upgrade to that! (Unless our barrel system works too good) Having said that, I want to ensure even though my compost is barreled, that we're still enabling aerobic composting within the barrels... I believe anaerobic would just build up too fast and I hear it stinks. If it stinks, I'll end up abandoning the whole thing. So here's the design I'm envisioning... Let me know if anybody has any concerns with problems I might encounter.

- Three 30-55 gallon barrels ( Part of me wants to go with as big as I can go to increase capacity for composting speed. Another part wants to ensure they're not so heavy that we find them too tough to move from the toilet room to the engine room. )
- painted black ( There's also the possibility of wanting to take the barrel outside into the sun in the summer if it might speed up the composting process )
- with a large pierced tube standing straight up the middle for more aeration
- and holes at the bottom (for aeration) taped up with cloth (to keep out bugs).
- To keep anything from spilling out or blocking the holes, I hope leaving some sticks at the bottom and a wire mesh covered in cloth on top of them will keep it airy.
- Once a bucket is full I can lid it with cloth and hopefully get large enough elastic bands to seal the cloth tight.

The pipe in the middle will be something I haven't seen done with a direct depository container before... perhaps for obvious reasons... Looking into your toilet and seeing a pipe poking up at you might not appeal... I'd like to just stick a lid on it while the toilet is in use (to prevent deposits getting in) and then remove it for better aeration when the barrel's full.

The rest of what's needed is mostly for aesthetics and sealing the box so that no bugs can enter.
- The toilet seat sealed
- The front wall should be removable to pull out the full barrel... How to do that and also make sure it's sealed...?
- The bags & bucket of carbon material with a little shovel
- a step ladder... to sit on top of the toilet over the barrel which can't be buried because this is a boat!

That's all I've got so far! My hope is that by the time the 2nd barrel is full, the first will have done a lot of composting already, without me dealing with smells or bugs in my living space!! If it hasn't, I may be able to send the barrel somewhere where it can finish its process. Give me some estimates based on your experience with these things on how much time it may take (in Ireland) for the bucket material to compost and be usable or at least decent looking enough to dump without offending.... If I was really successful, I would honestly use it to plant lots of flowers and keep them on the boat for watering Here are some of the resources I've been using for my research:

https://www.youtube.com/watch?v=lqbYohdTGzo - Composting toilet
https://www.youtube.com/watch?v=JAcEvs3Bxjs - How to Make Humanure Compost with a Composting Toilet
https://www.youtube.com/watch?v=JuKyhUVbKwM - Composting Humanure
https://www.youtube.com/watch?v=cAJ48HHflhY - Ventilation in a Compost Loo - How and Why
https://www.youtube.com/watch?v=rlml3Lmdv2o - How to Make a Compost Toilet with a Wheelie Bin
https://www.youtube.com/watch?v=Ul51Uz0qfHU&list=PLFD5D0CE103FD3A56&t=424s - Easy Ten Minute Compost Bin from Pallets
https://www.youtube.com/watch?v=bDmbdsry4Ro - E25 – Compost Toilet Ventilation Fan
https://www.youtube.com/watch?v=K4a3dTScBlg - How To Make A Composting Toilet
https://www.youtube.com/watch?v=FTt8OoHe4ho - How We Built A Compost Toilet Under $4 + Reclaimed Materials
https://www.youtube.com/watch?v=9huIfeFMBug - Composting Toilet Maintenance: Changing Barrels
https://www.youtube.com/watch?v=xOOUxa4_K1g - How to Build a Composting Toilet Barrel System
https://www.youtube.com/watch?v=BhhEGSvJYmc - How to build a complete composting toilet system with Pickle Barrel and Urine Diverter

https://humanurehandbook.com/humanure_basics.html - Humanure Composting Basic How-to Information
https://www.gardeningknowhow.com/composting/ingredients/composting-toilets.htm - Composting Toilet Systems: How Do Composting Toilets Work
https://thronecompostingtoilet.com/products/composting-toilet-diverter - Composting Toilet URINE DIVERTER – Throne Composting Toilet
https://www.ruralsprout.com/compost-toilet/ - Compost Toilet: How We Turned Human Waste Into Compost & How You Can Too
http://www.omick.net/composting_toilets/bucket_barrel_toilet.htm - Bucket-to-Barrel Composting Toilet System
http://www.omick.net/composting_toilets/barrel_toilet.htm - Barrel Composting Toilet System

Deirdre, That's a challenging situation!  I've been pondering what options you might have.  Keep in mind that hot composting is not the only option.  Here's 2 other options to consider:

(1) Bucket to Barrel Omick design: I've used his barrel design and the output material seemed clean enough for family to feel confident putting their hands in it and spreading it in the orchard.  In your situation I'm assuming it'd be easier to use a 5gallon bucket toilet and move the contents to aging barrels.  On his urine diversion webpage he indicates that the barrel contents can get too dry and what to do about it.  If you want to have your spreaded compost be unnoticeable I'd recommend preferring cover material that breaks down faster than sawdust.  I highly recommend the compost crank mentioned on his website.  If urine diversion isn't working well be sure to note his comments in the cover materials page about getting material that wicks/soaks up liquid well.

(2) Vermifilter: If you're comfortable regularly disposing of liquid, and you have enough room for some 55 gallon buckets, you may be able to use a wormed based flushing toilet design such as shown at vermifilter.com or vermicompostingtoilets.net.  While I have been delayed on implementing this myself due to our current low yielding well, I've studied many technical papers on it and worked with the owner of vermifilter.com on design plans. You may want to use a marine (lower volume flush) toilet and some sort of pump to aid in regular dispersal direct from the boat. With only 2-3 users you may never need to empty the compost.

Thanks @Burton, that omick article with the crank is quite insightful! Has me thinking about the bug problem& how to avoid it!

http://www.omick.net/composting_toilets/barrel_toilet_owners_manual.htm

One issue I have is that I really don't want the urine diverter inside the barrel. I had been picturing it in front with the barrel behind it, but I realise that actually leaves a gap for bugs to get in! I definitely don't want to try the worm compost option. It seems a little too advanced for me and heard that it's the one that fails most often, probably because it's just an extra thing to think about which makes it more complicated.

In our garden we have a very simple setup it is a bucket and a seat. the important thing is to get enough mulch and throw it on the top. You need a couple of buckets and a place were they can age. There are all these modern nappies they look like disposables and what I saw was that mums put one little disposable sheet of something in there and it makes it easy. Maybe wrap the whole thing in newspaper.

Deirdre, as an option to save on construction and look nice, you could just use something like a c-head toilet (example demo video) to separate urine and poop and then dump the 5gallon sawdust/poop bucket into whole 55gallon drums for aging.  As long as we use enough cover material the toilets really don't smell as my wife will attest to.  You do want to make sure you use the aerator though for the barrels to help ensure they stay aerobic.

Thanks Burton. I looked at the link to the product but seems extremely expensive for what it is. I will have help in the constructing, and finding materials second hand shouldn't be a problem. As long as I can have something working by the end of the year, I would prefer to construct our own.

I have been rethinking the barrel being in the boat though. There is some space at the back entrance to put one which would make the bucket to barrel system feasible. I was just resisting the idea of having to transfer the contents in case of any mess and because of the hassle. Having thought about it though, I could use a tall skinny bin that would be easy to empty into a wider barrel. That may reduce how often we need to empty & reduce the risk of mess in the process.

Due to some Hull repairs badly needed I haven't gotten started on this project yet, but I have been busy researching and I realised a couple of things. I was previously hoping to do the hot compost method and resistant in using worms. I see now why people stock up on their buckets as apparently hot composting should be started all in one go with a minimum 3 square feet, neither of which I have the space for.

When I saw just how quickly the worms break down organic matter I started to look into it more and sadly realised I cannot combine a worm and hot compost since they don't survive in very hot temperatures. So I'm back for advice from anybody with experience with vermicomposting.

I read that the compost may overheat for the worms and so they'll need a way to escape. I'm considering a double chamber system which I saw used in a very neat little kitchen unit, but that was for kitchen scraps not humanure! This would definitely have to go outside for me to add to whenever a bucket is full. Some of the warnings I've seen about worm bins is that you don't want to overfeed them & you don't want to trap them. But I'm on a boat so they can't travel through the ground from one bin to another. So now I'm trying to work out how to divide a barrel in 2, or connect two sealed bins so that the worms can escape the hot compost and move to safety.

Does anybody know how much is too much? Since we're dealing with humanure what kind of worms would be safe to use and is it good to load in my vegetables on top of each poop bucket added? Also, what are the right temperatures for worm compost? Can I just use traditional worm composting bins what can cause this type of system to get smelly? I'm in Ireland where it's pretty cold in winter when I'll finally hopefully have this all set up. Thanks for your input so far and any more advice anybody can provide.

Deirdre, keep in mind that hot composting is not the only method proven to reliably kill pathogens.  The Omick Barrel toilet design is a cold composting method that was certified by the state of Arizona to kill pathogens reliably if operated as specified (including the temperature and aeration requirements stated on the website).  Vermifilters are another cold composting method that has also been demonstrated to reliably kill pathogens using worms if operated as specified.  If you're set on hot composting with worms that can migrate between bins then you could consider using a pair of touching perforated bins that are enclosed together in an outer container as discussed here.  There are also methods of expediting the hot compost process which may only take a few days to process a batch.

To clarify, the barrel and worm methods reduce the pathogens to a "safe" level.  The barrel method produces compost that was rated safe to apply to landscape that is not growing food.  The worm vermifilter method at room temperatures typically results in about a 99% kill, which could be safe enough to use to grow food if you're healthy (ref).  Since worm vermifilters can be modular, each stage adds 2 more nines, e.g. 99.99% kill for 2 stages.  Hot composting on the other hand uses temperature (and time) which I believe is rated for absolute kill (100%), but the trick is getting every part of the compost to that temperature.

Burton Sparks wrote:The Omick Barrel toilet design is a cold composting method that was certified by the state of Arizona to kill pathogens reliably if operated as specified (including the temperature and aeration requirements stated on the website).

So this is the system I was initially considering before I actually entered the boat and realised the tight squeeze I'll be dealing with. It's a pretty spacious liveaboard for this country, but still, the ceiling is less than a foot from the top of my head as an average height woman (5ft 3"), and the doorways are not standard width. So moving these barrels around would be too difficult and there isn't the space to have them all inside, moving the toilet platform from one to the next. There is however space to keep 2 (possibly 3) at the front of the boat, but it would mean doing "bucket to barrel" since they're all kept outside in view.

Permaculture is totally new to me so excuse my ignorance. I presumed that this was also a hot composting method. It does say "it must be used in mild climates to insure sufficient heating for effective composting" and the guide to appropriate climates recommends "average temperatures of 50 degrees Fahrenheit or higher during the 4 coldest months". In Ireland it gets as cold as freezing or averages around 32 - 41 degrees Fahrenheit at its coldest. This is what makes me think I would need to combine vermicompost with hot compost, since we get cold enough for the worms to survive in winter, but I'm unsure that it won't overheat in the summer. It's also not going to be possible to move from one part of the boat to a more or less shaded part if I'm dealing with large containers.

Burton Sparks wrote:Vermifilters are another cold composting method that has also been demonstrated to reliably kill pathogens using worms if operated as specified. If you're set on hot composting with worms that can migrate between bins then you could consider using a pair of touching perforated bins that are enclosed together in an outer container as discussed here.

This idea sounds great up until it advises that I need a whole metre squared of surface area for each compartment... Space I just don't have at the bow where I was hoping to put it. I could possibly fit it higher up, if I install something to flatten the surface below the containers. (The roof has a slight curve toward each side). But of course I couldn't pipe it from the bathroom like they suggest in the article you linked. I'd be emptying buckets into it manually.

Burton Sparks wrote:There are also methods of expediting the hot compost process which may only take a few days to process a batch.

I appreciate all the advice! I'm enjoying learning about this although I'm sure I'll realise the experience of actually doing it will be the greatest learning curve! I wonder if the vermidigester would work just as well with the red wrigglers in higher containers, as it'd be a lot easier if I could fit the system on the bow. What are your thoughts on their recommendation of using earthworms with wider surface area? Thanks again for all the tips, and any more methods on expediting the process whenever possible is much appreciated!

Deirdre, welcome to Permaculture!  I'm calling "hot composting" the range of temperatures where heat is used to kill pathogens over time (e.g. 115F for 7 days or 143.6F for 1 hour).  That can occur as a result of the compost heating itself up or with your helping by adding heat, insulation, or a certain amount of air to carefully blow the bacterial ember into a roaring fire.  I'm calling "cold composting" anything between hot composting and freezing temps where the strategy to kill the pathogens is by creating an environment that favors the good guys.  In the case of worms, their sticky mucus is both antibacterial and enhances the ability of the media to hold onto pathogens until the worms can eat them.  The gut of the worms not only kills them directly but also favors good guys.  The net effect of careful use of worms is treatment of the effluent in minutes, you'd only have liquid output to deal with, and the treatment is hands off.

Effective worm composting takes place around 50-90F, less effective below comfortable room temp, and they can die above 100F or down around freezing.  Having said that, the periodic flow of room temperature water from a toilet through an insulated worm bin has been shown to greatly help keep the worm bin in a temperature range that is effective for worms even when installed outside.  I would think building it on the bow of your boat could work fine if the flush water could be moderated a bit.

For a primary vermifilter treating blackwater you'd want at least 1m^2 of surface area.  More surface area and ensuring the media isn't too fine or matte down are strategies used to help ensure the system doesn't get clogged and kill all the worms (I wouldn't use leaves).  More surface area also reduces the likelihood that you'll ever have to empty the vermifilter.  Media that breaks down faster (e.g. wood chips vs gravel or bark) similarly reduces the chance that you'll ever need to empty the vermifilter, but at the expense that you'll need to top off the media every few months.  You'd want at least 1m depth to include both media with the worms and room for the pile to grow.  The action of the flushing water will help the worms spread the deposits.

If I only used a primary (first stage) vermifilter I'd want to use a sump to allow me to pump the treated effluent to the land.  The sump could be as simple as increasing the depth of the primary vermifilter container by 1ft and using a plastic pallet inside to hold up the media to create a void at the bottom for the liquid to collect in.  If you wanted to have the option to send any excess you didn't use back into the river I'd recommend running it through at least one more stage coupled with plants.  Why plants?  In addition to helping reduce pathogens they perform a complementary treatment by reducing the nutrient load to near perfect in my mind.  Certainly way better than flushing raw sewage into the river.  I've looked into doing something similar in reusing the treated effluent for a pond for our geese and ducks.

As for sawdust, I was actually considering collecting leaves in the autumn

I don't have any life experience composting human poop with worms when a time limit is a factor but- Shredded damp leaves are the best if you go with worms, based on experience (mine and many others). They thrive on leaves!
There is a website (I'd post a link if I could remember) that demonstrated a flush toilet linked to an IBC tote that had leaves and worms, and then a drainage into a plant filled swale. I know you can't do that, but it gave a lot of good info on the worms.
The space on a boat is at such a premium that disposing of waste via composting may be a difficult juggling act. Worms will probably be the fastest method other than burning (is a mini incinerator possible?). If you had 2 containers, how often could you get to land where you could spread the contents of the aged one (saving all the worms of course!)?  I'm guessing a 55 gallon container would hold a 30 day accumulation, then 30 days to decompose a bit. With some diligent inquiry you might (might) be able to find someone who would actually want the aged stuff for an orchard or other area where the crop grown is not consumed directly from the soil.
I wish you well, especially given the exhaustion that comes with a newborn. This definitely sounds like an adventure!