Add any comments relating to design of compost toilets
what is the article about?
What an effective design there, right?
What a simple, effective system. Very impressed. I do have some questions about the “plastic tap” to be included in the wheelie bin. The instructions say to include one but don’t specify what, exactly, it is. I gather it’s a spout of some sort- I assume I need to be able to close and open it? So I drill a hole in the bottom of my wheelie bin, then what do I use for the tap? Could you also clarify when it should be drained? Only occasionally during the 1 year compost phase, or at other times too? Thank you!!
Kia ora Megan,
The wheelie bin and its contents is not under pressure as such, so it doesn’t really spout.
We have been using boat bugs lately, as taps have been a little issue at times being easily knocked off. There is a boat bung that has a standard BSP thread, so a tap can be threaded into the wheelie bin. Here is a link.
Any tap is suitable.
It doesn’t need to be drained often. You usually notice if it has really high levels of liquid, because it becomes super heavy and hard to move. This to us, means more sawdust needs to be added or improved urine separation. We usually only drain it a few weeks prior to us empting.
hope this helps.
I want to set up a composting toilet on our rural property at Ruapuke. Previous owners built a long drop – which is problematic due to the clay soils and slow drainage.
I’ve decide that bucket system with a wheelie bin composter will work well considering we are not there fulltime and the loo won’t have high use.
I have seen your designs for an emergency wheelie bin systems – but have a few further questions. I have some punched ag pipe to provide airflow in the bin and will fit a tap at the bottom for drainage and add a meshed overflow pipe near the top of air flow into and out of the bin. Should I connect the internal ag pipe to the vent to the outside, or is being close to the opening enough? Also wondering if I should connect the overflow pipe vent to an external chimney type pipe to assist airflow and reduce potential smells? Any chance anyone runs workshops about composting toilets here in the central north island?
Any suggestions with my design is appreciated.
Kia ora Nicky,
Thanks for your questions and great that you are constructing a compost toilet. We don’t know anyone in the central north island, but will put the word out to a few networks to see if anyone in the area is able to provide help or can show you there set up.
With the design. The only issue we have found with this type of system is that the ag pipe is something that has to be handled at the end and hosed out type thing for the next batch. We have found clumping semi dry sticks to form a tube type thing really good. This way the whole contents of the wheelie bin can be emptied out and no handling of air flow pipes. Personal preference though.
With regards to connecting the ag pipe to the vent, I would not recommend this, as the evaporation from the top of the pile is just as important as the bottom, so allowing free flow of the air out of the vent at the top is a good thing.
Having the vent pipe connected to a chimney is a good thing, in that it will draw more air. However, I have understood that you are using a bucket system and then transferring the contents into the wheelie bin after. If this is the case I would not worry, unless you are depositing directly into the wheelie bin. Chimneys can be a hassle to connect otherwise.
hope this provides some help. Feel free to write more questions and I will respond via privat email, then I can call you if required to discuss. Good luck
Given me something else to consider with my loo. Not quite ready to build – collecting the bits and pieces as I find them at the dump shop! I will get in touch if I have any further queries.
Thanks for your thoughts.
Yes the separating of pee and poo is a bit more cumbersome. When I deliver our workshops on how to make and manage an emergency compost toilet, I usually explain both ways. The separating system is basically more suitable for an emergency situation where people are using wheelie bins or buckets for a couple of reasons:
– a wheelie bin is a small container and keeping the pee out of it means that less mass is going in, and so it will take longer to fill it up.
– a wheelie bin is basically sealed and evaporation is low. by seperating the pee out it means you have greater control on the moisture levels going into the bin. You can always add pee in if it is too dry, but they only way to get a really wet mix drier is to add more sawdust and then you bump into the bulking up problem discussed above.
I like the idea of using a wheelie bin in an emergency because it means that it is nice and sealed, so that if people loose interest and don’t do it well (there is a lot of other stuff going on in a post-emergency situation) it is all safe and sealed and not going to cause contamination problems. Also, there is also the possibility that a municipal authority could collect and compost the contents centrally since wheelie bins are easily transported.
In my own personal home set up, we do not separate, and we use a basic 20L bucket system. But we are composting in a nice big outdoor compost, with a really thick biofilter at the base, and plenty of space for lots of bulking material. The pee is really high in nitrogen so having all of it in there increases the chance of getting a hot thermophillic compost. I have been measuring the temperatures and am just reaching the thermophillic temperatures.
Whether you separate or not, really depends on your situation. And an emergency is quite a particular situation. Our current workshop booklet – available on the front page of this website, explains both techniques.
I say put everything into a single bucket. Use enough absorbent below and enough cover above to handle the smell. Empty the bucket as often as necessary. I do and I get excellent results. I have left a mostly full 5 gallon bucket with everything in it for weeks and no smell. There may be some smell when you dump it from the saturated part at the bottom but that stuff then winds up on top of the pile which helps to equalize moisture distribution within the pile.
I basically would not bother with the system if I had to fiddle with buckets of pee and I’m not particularly squeamish. If you’re going to sell this successfully to the masses it has got to be simple and not challenge the basic conditioning they received during potty training too much. I do see that the problem might arise of particularly sensitive individuals using up a half a bucket of sawdust in their zeal to hermetically seal the waste, symbolically if not in reality.
I am not saying the system can’t be screwed up. I can see for example teenagers using the system a lot but never troubling to empty it, using less and less filler as the bucket got more full. Under those conditions it would get overloaded and it would smell. The failure at that point would be that it was not emptied. I see this as a system that would not work in a public environment for that reason.
Thanks for this website! I am so happy to read this information. I live in a city terrace house with a completely concreted courtyard, but I’ve got a composting toilet going. Our model is almost exactly like your design for the wheelie bin (with the false bottom and tap installed, and the aeration pipe), except that we shit directly in the bin, rather than into a bucket. This avoids the need to transfer it to the bin. (The downside is that we keep the wheelie bin in the shed, so we have to leave the house to go to the loo – but that’s no problem, really.) I didn’t see any mention of this idea (shitting straight in the bin) on your site. Is there any problem you see with it? We’re nearly full and about to add some compost worms and close the lid for a year. I was wondering what to do with the tap. Should I leave it open (we have a hose that drains into a tray filled with sawdust, but so far we’ve had no leachate – I suspect that may change once the worms get at it)? Or close it, and open occasionally and then pour the contents of the tray back in?
Thanks for your feedback and exciting to hear what you are doing.
A few comments to respond.
We also shit straight into a wheelie bin as it is easier and less maintenance than having to empty the bucket etc, however for an emergency solution and for people who are not that committed to the cause, being able to excrete inside the house (esp. in these colder months in Chch) and not having to build a structure around the wheelie bin and take up a large portion of their garage/shed.
The other side to it is that using the bucket system you can fill a wheelie bin to near the top, where as excreting straight into the bin means you have to stop when it is 3/4 full, otherwise it gets a little too close for comfort. If doing it by the book and through the authroirites you have to ensure that the shit, depending on the council, is around 400mm from ones bottom when excreting.
Condensation on the bottom of the toilet seat (in wetter climates) is another issue which is resolved with the bucket system.
So all in all, no problems going straight into the wheelie bin. I do recommend venting it however.
When you take the wheelie bin out of the shed and start the real composting, liquid will start to form in the bottom. I recommend keeping the system closed rather than draining the liquids off into sawdust. This liquid will likely contain the pathogens that are present in the shit an therefore in your bodies.
What we do is keep it closed and drain it off at required intervals and then tipping it back in the top, but adding more sawdust/brown material at the top to absorb some of the liquids. This way you allow all the contents to spend the months required to become pathogen free.
We have got a really good system at home though, which is based on this system which I can go into detail about at some point soon. We do hope to update our website soon, with our updated information and slightly tweaked designs and also including other types of composting toilets that people can build.
Please if you feel like posting some photos that would be awesome.
Enjoy the process and happy to help, how ever we can.
Great information, thanks. One question: Using the wheelybin system, the lower 150 mm collects any excess moisture and the composting takes place above. Shouldn’t this excess moisture be drained off from the bottom of the wheelybin before the composted contents are tipped out? Presumably this liquid will be full of contaminants, so what is done with this liquid?
We have fitted some taps on the bottom of the wheelie bins. If a tap is fitted any liquid that is extracted can simply be poured back into the wheelie bin, and abosrbed by the composting materials.
What a great website!! I’m not in Chch but wanting to set up a composting toilet on our land where we camp for holidays. I don’t have access to wheelie bins so I’m looking at some 200l drums instead. They have airtight lids sonim wondering whether I should drill some hes in the dudes or just have the pipe poke out through the lid or … ? How much air do they need? thank you for any help!
Oops! Damn autocorrect! That was supposed to read: “so I’m wondering whether I should drill some holes in the sides or….”
I have been using a composting loo for the last year and love it 🙂
Being a female I do like to pee and poo without moving to a different bucket. I solved this by cutting the bottom off a bucket and attaching this to the plywood under the toilet seat, this bucket slots into the bucket that contains the poo (the toilet is raised quite high so as the cut off bucket only just enters the poo bucket). I then attached a funnel with a hose that goes through the wall of cut off bucket and into another container. So you pee in the funnel – move back a bit and poo into the main bucket. I have seen variations using cut off bottles, it just depends on what resources/money you have available.
I would also recommend using partially decomposed saw dust rather than the fresh stuff as the fresh stuff can take years to properly break down, whereas the decomposed it part way there. You can get the decomposed sawdust from most sawmills/firewood suppliers.
And I would also recommend adding a tablespoon of ash or lime after each poo as this ensures no flies will go near and it gets rid of any smells that do appear (particularly in warm weather).
And another design thought – my set up uses 56L rubbish bins rather than small ones. This means that I keep using it till its 3/4 full, drag it out, put the lid on and leave it to compost. The only time I empty a container is when its fully composted. Saves time and the ick factor as I don’t have to empty small buckets. I have a rotation of 8 bins. My set up is outside though – this system probably wouldn’t work for those who want it indoors.
Love this site by the way 🙂
Great to get your feedback and exciting about your interest and keenness to assist.
To respond to a few of your questions
Whether male or female, one can not always be sure to not be pooing and peeing at the same time. What we suggest is people use the pee bucket when they know they only need to pee and use the poo bucket any other time. Some urine in the poo bucket is ok, but too much means an anaerobic system (without oxygen) which results in smells and gases, higher pathogen risks and a entirely different composting process. Any liquid passing through the poo bucket potentially contains the pathogens, so separating prior, results in a better composting mix.
We are having conversations with the City Councils and also hoping to further conversation with ECAN who are the regional council in Canterbury who deal with consenting of compost toilet systems. These processes take time, which is good for allowing us to thoroughly research the most resilient and appropriate system for everyday use and disaster events.
Next time we are in Otautahi/Christchurch it would be great to meet up and discuss things further and share the stories.
Thanks again for your feedback and we will touch base when we return to Chch next.
There is a lot of speculation here on whether adding urine could increase the risk of pathogen leaching. I am wondering whether there has been any research into this or whether everyone is just guessing? Has Joseph Jenkins’ idea of a thick biological filter actually been tested experimentally?
We also use Jenkins’ design, putting everything in (faeces, urine, dead mice, toilet roll tubes…). I am not concerned about leachate in our case as we are on heavy clay soil, with the nearest waterway a hundred yards away, but it could certainly be an issue in Christchurch.
If you expect people to actually change to a composting system, the more similar you can make it to the flush loos they are used to the better, and having to separate urine and faeces is a level of detail that puts the squeamish masses off unfortunately. If Jenkins’ idea of putting everything together is environmentally acceptable, it could get far wider adoption than the two-bucket system being promoted here – but we really need some research data to back this up.
So true Samuel and thanks for feeding back.
Urine passing through fecal matter results in that leachate liquid having a high chance of carrying pathogens, if they are obviously present in the fecal matter to begin with.
We haven’t yet found any research on this, and Joseph Jenkins has not had it scientifically tested either.
This is something we would like to embark on, but do not have the funds, however we are trying to step into this arena. Any help would be great, especially contacts in the industry. Do you know of anywhere that maybe able to assist us in this pursuit?
I think it is important to manage the leachate, no matter what the subsoil and waterway distances, because its all connected and for the reason that we are obviously concentrating the levels in one area, so contamination risks are higher.
I agree with not separating urine from faeces for convenience reasons, however in urban scenarios where risks are higher and where we want the optimum moisture levels for aerobic composting in an enclosed chamber, adding urine is a problem.
With regards to behavior change, I think it is important to make it clear that it does not matter if you urinate into the faecal bucket occasionally. It is sometimes unavoidable…but when it is obvious that you only need to urinate (without the bowel movement pending) then it seems not logical to put this moisture into a system that can not handle it, mainly because it is enclosed.
What testing we have done is the amount of sawdust/wood shavings are required to soak up a 500mm of urine. It is a lot, especially to create an aerobic system. Its more than your average handful that most people put in.
Amongst our team we have these discussions regularly, but know our next step is to test the systems to know for sure. Ultimately the thermophilic conditions is what is required to ensure risks are very minimal, however this is rarely obtained in most peoples backyard composts. They need to be batch produced, 1m sq minimum and managed well.
Thanks again for your feedback.
This is research I’d be keen to do myself if it doesn’t exist (I’m a soil scientist based in Lincoln) but we’ll need to find funding. Government research money is available, but mainly to top up industry contributions. You’ve got my email address to discuss it further.
To explain better our situation with clay, yes everything is connected ultimately, but it all depends how much topsoil leachate will pass through before hitting a sensitive environment. We have a poorly permeable and very deep clay subsoil, so leachate will reach that then move sideways through the topsoil, and since topsoil is a better treatment plant than anything man can produce within a few metres it would probably be drinkable. This is completely different to Lincoln or Christchurch, with gravel subsoil, where leachate will primarily move straight downwards into the shallow aquifers and then potentially into lowland streams. Soil type has a major impact on system design.
It does take a lot more sawdust when all urine is going into the same bucket. I am considering making a male urinal piped directly to a garden to use the nutrients – essentially achieving the system Nandor Tanczos describes below without freezing yourself on a frosty morning and while keeping it familiar for squeamish visitors. But we don’t have much space in our bathroom unfortunately.
This conversation was continued through email, as I wanted to ask Joe about some other things, as well as getting to the bottom of his comments about urine seperation…
Basically I’ve realised that if you are trying to get a hot (thermophillic) compost, then Joe is right. The urine is what provides the nitrogen and the heat which kills the pathogens. A hot compost system needs sufficient mass to get going. So for it to work you need to have enough humanure going in at one time. If there are only a couple of people in the household (like at my house) then you can get around this by storing your humanure mixture in buckets with lids and adding it to the compost in batches. We are trying 4 buckets per batch at the moment, in our big outdoor compost bin and hoping to reach thermophillic conditions.
The other option is to go for a low-termperature worm based system, rather than going for a hot compost. The worms don’t like the urine so much, so it pays to seperate the urine and poo as much as possible. The wheelie bin system that we were showing people how to make after the earthquake is really this kind of system. There were a number of reasons why we chose this system. We were taking into consideration the high water table, the materials that people had available and ways to minimise contamination risks. So if you have been using this kind of system, consider adding in some tiger worms to give it a boost, and make sure you leave it long enough before using it on the garden (1 to 2 years).
Yeah good question, and one that has come up a few times. The design that we have been suggesting uses a wheelie bin for the composting process. Since it is a closed system it removes the risk of the leachate. However, it does isolate the compost from worms and such, which can be remedied by adding some mature compost and wormies to the bin. It also reduces the likelihood of being able to reach thermophillic (hot) conditions, which isn’t necessarily a problem, it just means you have to leave it longer to make sure all the pathogens are consumed.
If you do end up having an open system there a few things you can do to lessen the likelihood of leachate.
– add extra sawdust if you are peeing into the humanure. This will soak up any excess moisture
– create a really big biofilter under neath the pile, made of absorbedant, coarse materials like straw or hay. Joseph Jenkins reckons the bio-filter can even be as thick as the whole compost heap, because it will compact down when material is added to the top.
– dig a dish shaped depression underneath your pile. This means that if any liquids do make it through the pile, they will not leach out sideways.
– cover the pile, during periods of high rainfall.
– The top of you pile should also have a really thick bio filter (more straw) which should soak up some rain, and will keep any other creatures out of the centre of the pile where the humanure is composting.
Hope that helps Kevin. Greg and I are coming to chch next week to do some composting toilet stuff. Get in touch if you’d like to catch up then.
I read the Humanure Handbook and really felt the writer spoke my language and would like to follw the system that he used. Obviosly there is the issue of leechate. regarding living in an urban environment. I was also inspired by the fact that Nandor Tancsos has been composting his toilet for 5 yrs and would like to implement a system that could be permenent; so. considering this. what would be the legal and socialogical issue of having a collection system that used a biological leechate barrior that allows Mother Earth’s worms and what not to pass into the compost?
I live on Marine Pd on a rather long block and own the land.
I use a receptacle for only urine in a small room off my bedroom and have done so for decades and there is no smell, so I don’t know why people keep saying that urine should be separated because it causes odor. Of course, you have to keep a clean layer of sawdust on top of the receptacle contents at all times, which is the same routine for any compost toilet. Also, the urine makes the compost work better, so the argument that it should be separated to prevent pathogens is not true. You want to make hot compost and you will if you include the urine. It’s the hot compost that eliminates potential pathogens, not urine separation. Go to urineseparation.com for more information.
thanks joe! and for all your designs and great work and encouragement of these processes. your book the humanure hand book was gifted to me 8 years ago and its one of my most loved books. awesome 🙂
I use the wheelie bin concept, however both liquid and solid into the same bin. There is a verticle divider that sends the liquid to the bottom and the solids down the back to the mesh. I place some Bokashi medium on top of the solids to aid the decomposting process which also removes smell. I have a small slider on the composting side that allows for removal of the part composted manure for further storage until the process is completed. BUT it is also easier to have two bins in the process. I am trialing the new smaller bins that are available at the warehouse. The liquid chamber has a small tap on it which allows ease of draining this into a bucket when needed.
I believe Joseph Jenkins says to pee in the same bucket. I have been told that the high levels of ammonia in the piss makes the bucket smell but my guess is that adding more sawdust will solve that problem? I can see no reason not to add piss into the bucket, except too much moisture in the compost pile? Please give me your opinion on the disadvantages of adding piss to the bucket and then the bucket to compost pile. I am just starting to implement this and it would be good to hear what you think.
Great news that you are starting to implement a compost toilet.
You are right in that the liquid can be composted like Joseph suggests, however that is where lechate and runoff are not a problem.
As soon as pee passes through the poo, the pee is potentially containing pathogens, whereas pee on its own does not create this risk. So this is the main reason to compost the poo seperately. To ensure you get rid of the pathogens it needs to compost for at least 9 months.
Pees can just be spread safely onto the garden, but best to do within 24 hours, so that the nitrogen doesn’t evaporate and this also keeps the smell down. Also best to dilute before spreading.
I can give you a few more references, but will have to be in a few days. Thanks for getting in touch.
For about a couple of years I have been using a bucket system (as http://weblife.org/humanure/chapter8_2.html) where I empty the bucket about weekly into a large compost container for it to mature. I keep urine out as much as possible by asking guys to pee on a tree. Women tend to want to use the toilet though for obvious reasons. I have found that having a lot of urine in the bucket makes it smell alot more and makes emptying it, which is usually mildly unpleasant, considerably more so. You could add more sawdust but the liquid collects from the bottom up, making it harder to soak up, and I already go through quite a bit of sawdust as it is.
The comment above about the pathogens is interesting, thanks.
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