“The world is divided into two categories of people: those who shit in drinking water and those who don’t.” – Joe Jenkins, the Humanure Handbook
What are compost toilets?
Compost toilets are dry or waterless toilets, i.e. they don’t use water to take the waste somewhere else. They allow natural processes to produce useful compost, after a resting period depending on the type of toilet.
DIY compost loos
There are usually two chambers – one in use and one resting. A typical toilet would use one chamber for a year, then change to the second chamber and allow the first to decompose for a year before emptying. They don’t smell, as long as there is a vent pipe, and a drain to take away excess liquid.
A handful of a soak (straw or sawdust etc.) is dropped into the toilet after each use. This is because bacteria like to eat a balanced diet of carbon and nitrogen, and as human waste contains a lot of nitrogen, if they don’t get enough carboniferous material (like sawdust, straw, hay, shredded paper) they will give off excess nitrogen in the form of ammonia, which makes the loo smelly.
The soak allows oxygen into the pile, and absorbs liquid. This allows the pile to decompose aerobically to produce nitrates, phosphates and sulphates. Without a soak, the pile will decompose anaerobically and produce methane, ammonia and hydrogen sulphide – all smelly and not very useful.
Human pathogens don’t like conditions outside the human body, so almost all will be dead after a few hours. Only one type of roundworm egg can survive a year-long decomposition period, but to cause problems for humans, it has to survive decomposition and being outside in the soil, after which it has to get onto the food plant, and stay there after washing and cooking. You’re taking much more of a risk every time you get into a car. But even so, you could use the compost on fruit trees and bushes rather than in the vegetable garden if you like.
A tree bog is a type of outdoor compost toilet with nutrient-hungry trees planted around it. Solid and liquid wastes are simply deposited into a hole in the ground, and the tree roots absorb the nutrients.
Another, simpler compost loo system is based on Joe Jenkins’ ‘humanure’ idea. It’s low-cost, extremely simple and it works. The downside is that there are buckets to be emptied. Here’s an article about some friends of ours who used the humanure system for many years.
Off-the-shelf compost loos
You can also buy off-the-shelf toilets with one chamber – for inside or outside use.
What are the benefits of compost toilets?
- The solid waste is dealt with on site, and doesn’t have to be treated with chemicals in sewage farms, or end up in waterways, where it causes pollution and algal blooms.
- Saves water – you don’t have to use one resource (pure drinking water) to flush away another (fertiliser).
- Organic matter is allowed to go back to the soil where it belongs, improving soil structure and nutrition.
- No chemical cleaners or bleaches are used in the toilet.
- They don’t contribute to the sewage sludge that is often dumped in landfill, or more controversially, put on to agricultural land uncomposted.
- As long as the decomposition is aerobic, there will be no greenhouse gas emissions.
- No electricity needed.
- Very low resource use – no pipes are needed to transport waste to a sewage farm, and no truck needed to remove solid waste.
Introduction to our compost toilets online course.
What can I do?
Installing a compost toilet
There are many different types that you can buy. Distributors will change – search online for:
- Separett – looks like an conventional toilet.
- Air Head – small enough to be used in a camper van or boat.
- Rota-loo – several chambers on a turntable, includes a fan.
- Biolet – small toilets, some models electric, some not.
- Clivus multrum – one large chamber, vent with fan.
- Sun-mar – small, electricity used to evaporate liquids.
- Natsol – twin-vault loos with stainless steel urine separator.
- Kazuba – high-capacity, for allotments, public spaces, off-grid sites.
There are many more, with new models coming on to the market each year – do the research to find which model might suit you best.
Alternatively, you can build your own. This will work out cheaper, and there is no need for electricity. The components of a basic unit are: two chambers, platform, vent, hatch, and removable seat. See resources for books, courses and online course.
Using a compost toilet
A compost loo is not a flush-and-forget system. A DIY compost loo needs to be checked every day to see that no problems are developing. If necessary, an ingenious fly-catcher can be made from a glass jar and a little cone made from perspex. Ensure that there’s a bucket with ‘soak’ (e.g. sawdust) next to the loo. To stop a peak developing, it may have to be ‘knocked’ every couple of months with a rake or hoe either via the hatch or seat – this may not be necessary though.
Waterless urinals work well with compost toilets, as urine can be used as a completely-pathogen-free fertiliser, and it stops the compost toilet from becoming too wet. Waterless urinals can be adapted for female use too. Some compost toilets are designed to separate urine from solids (see links page).
If your toilet is going to be used by people unfamiliar with compost loos, you might want to put up a notice explaining how to use it.
After the toilet has been used for a year, remove the seat and blank off the hole. Attach the seat to the second chamber. One year later, empty the first chamber and move the seat back. The material from the chamber will be indistinguishable from bag compost bought from a garden centre if it’s done properly. We’ve taken compost from a compost loo and from a garden centre to events around the country, and people couldn’t tell the difference.
The procedure is different for various kinds of manufactured toilets. See further info for more on getting and using a compost loo, and see our online course for more detailed info and videos.
Whilst you’re here, why not take a look at the other utilities topics available? And don’t forget to visit our main topics page to explore over 200 aspects of low-impact living and our homepage to learn more about why we do what we do.
The specialist(s) below will respond to queries on this topic. Please comment in the box at the bottom of the page.
Patrick Boylan has had a long-term interest in the environment. A graduate of the Trinity College Dublin Botany Department in 1998, he founded Toilet Revolution in 2012. Patrick has researched manufacturers the world over, and Toilet Revolution have hundreds of composting toilet installations around the UK and Ireland.
Cordelia Rowlatt of Vallis Veg lives off-grid on a small piece of land. She has built and used many compost toilets for different situations, as well as lived toilet free when travelling with a gypsy circus – lesson learned: never take your toilet for granted! She also uses processed urine and faeces to feed crops safely. She’s our online course tutor
The views expressed here are those of the author and not necessarily lowimpact.org's
67 Comments on Compost toilets
Rob Chambers, composting - May 13th, 2016
Just implemented a new design that has been used for hundreds of years. It’s rather troublesome because the maintenance is somehow tedious but I think it’s worth it if you’re aiming for a low-impact living. Plus you get sweet compost and no waste is wasted. 🙂
Rob, gardener & compost expert at http://www.gardenersserviceslondon.co.uk/
Anne Chapman - October 10th, 2016
Has anyone heard of compost loos catching fire? We own a small bit of land in Cumbria and had built a compost loo there, using a natural rock outcrop – you walked into the toilet at the top of the rock outcrop and the toilet was over a drop of a couple of meters, with the deposits being retained by timber sides. It had been there some years and was just used intermittently. However, in July this year we visited and found it had burnt down – all that was left was a few blackened bits of timber, and not much of that. One possibility is arson, but it’s a pretty out of the way place and there’s no other evidence of people being around, such as rubbish left there. Is it possible that it has spontaneously combusted? The loo seat may have been left up and if the wind was in the right direction it may have blown up through gaps in the timber and perhaps led to the compost etc. catching fire? Once it got going the structure would have acted like a chimney, and the whole lot burnt. The surrounding vegetation is pretty much unharmed. Has anyone known of something like this happening before?
Dave DarbyOctober 11th, 2016
I’ve never heard of it and I think it’s pretty unlikely. First, the decomposition would have to be anaerobic to give off methane, and so would have to be waterlogged or in a sealed container. If it intermittently used, with timber sides, it wouldn’t be waterlogged. Then there would have to be a spark or a fire – maybe someone throwing a finished cigarette down the loo. But it’s quite difficult to start a fire, and there almost definitely wouldn’t be any methane produced anyway, so I’d say arson was a lot more likely than spontaneous combustion.
Ollyoop - December 21st, 2016
hi i’ve seen systems that seperate the urine from solids. is this necessary? or can it all go into the one tank?
Dave DarbyDecember 21st, 2016
It can all go to the same place as long as there’s a drain at the bottom. If it gets waterlogged, it will become anaerobic and smelly. So there needs to be a drain, or a urine separator, or try to wee somewhere else (on a straw bale is good – turns to compost eventually), or a waterless urinal?
DiHammill - February 18th, 2017
Hello, Im looking into either bought or home-made compost loo for our tipi site teaching sustainable living and want to know if we made our own (we would rather go for a bought one but the prices are dear) – what is the vessel people use for he chamber? A wheelie bin with holes in sat in gravel with eg. willow growing would that do – say two next to each other to allow the one chamber to compost while the other is in use? Chamber advice please!? Di
Dave DarbyFebruary 20th, 2017
You could certainly use a wheelie bin, as long as there’s a drain, as you say, and as long as straw, sawdust etc. is used to add carbon. Then when it’s full you could wheel it somewhere to break down for a couple of years.
Or – you could just dig a pit (as long as it’s more than 10 metres from a watercourse. Liquids will drain away, cover it over when full, and if you want to, you can dig out the compost after a couple of years.
Patrick Boylan - February 20th, 2017
There are a couple of differences between the off the shelf toilets and the home made. Venting. It’s important to get the vent flue to come directly out the top of the container to minimise odours, as opposed to coming out the side. Thermal Insulation, if you want the material to break down in the toilet then the compost pile will need to be above 13 deg C. This can be tricky to achieve as you must try and get an air tight seal between the top of the container bin and the underside of the toilet seat support. If you don’t all the heat will be lost and the compost will chill. But this may not bother you as Dave suggests you could just allow the material to break down over a couple of years and use a number of new containers. The off the shelf version overcomes these issues. On the idea of digging the pit, I think this is a risky option. The problem is that the base of the pit should be 1.5m higher than the high water table level. The high water table level is the level of the water table after a long rainfall event. If you don’t get this clearance, faecal matter could get on to the water table and contaminate drinking water for several months.
Graham Suddick - May 9th, 2017
Here is a UK company making eco loo’s: http://www.kildwick.com/
icarus - August 28th, 2017
The one important item missing from these toilets is a chimney pipe. It connects to the waste can just below the lid. Its purpose is to draw air into the toilet pan and thence out up the chimney . The result of fitting a chimney is that there is no odor even with a poorly fitting lid as air is constantly drawn into the toilet, Even when you lift the lid there are no nasty smells rising from the pan
icarus - August 28th, 2017
whoops just read the earlier post where Patrick has covered this excellently
icarus - August 28th, 2017
if your house has mains sewerage connection is there any legal obligation to use and pay for it or can you cap it off and notify the water authority their service is not required ???. I have commenced disconnection from the drainage system . Roof rainwater now is pumped to a storage tank with an overflow that finally terminates in a soakaway.
Patrick Boylan - August 29th, 2017
Sounds like an excellent system you have installed there. Is the rain water harvesting system got a mains top up for dry periods? I assume you have a water meter which is reading near to zero so is it the standing charge you are trying to avoid?
icarusAugust 31st, 2017
I didnt want to top up from the water mains and at approx 1kg per litre i opted for ground level storage outdoor tank.I use a dual shower pump and pressure switched expansion tank to feed water at 3 Bar to house for good shower and working taps with no plumbing changes After pump supply goes through double check (1 way) valve to a tee The water meter feed goes directly into a second double check valve outputs through an electrical solenoid valve then to second leg of the tee.The output of the tee or feeds the whole house( apart from filtered drinking water taps fed solely by water meter). My supply conforms to uk water regs as it is isolated from supply water mains . to use rainwater electricity is supplied to the dual shower pump to use mains water the electrical supply is removed from the shower pump and connected to the solenoid . This can be done by a change over switch or relay . .My storage tank a recycled 1200L IBC has a float switch about 2cm from the bottom to automatically switch over to mains water when the tank is emptied to its last 50 L. . I worked in electronics industry, having escaped from the family plumbing and building business .There is no need to build a controller from individual electronic components as float switches and relay driver boards are available ready made at low prices . I just box them into nice looking electronic controllers. I am willing to supply full parts lists wiring diagrams and supply sources for UK if anyone wants to build their own controllers Yes I want to avoid the standing charges
icarusSeptember 8th, 2017
the reasoning behind building my own toilet was that the ones i had seen were over complicated way over priced and quite ugly!. The ones i have briefly looked at on your web site look well designed beautifully made competitively priced ,The best of all though is to be offered such a superb range of products by what is a dedicated superbly knowledgable expert company- they look fantastic ! . If i was paid by a competitor . to give adverse criticism the only thing i could write would be “This company should be known to many more people across the whole uk”.
icarusSeptember 10th, 2017
patrick ,Wow that is one superb crapper collection they look well made and reasonably priced .The inclination to make my own is waning , congratulations on an excellent range of products . I will be enquiring soon .
Patrick Boylan - September 6th, 2017
Heyup, i wouldn’t be an expert on legionaries treatment. I suggest you post a question on http://www.susana.org/en/ . The level of knowledge on this blog is PHD ++, really knowledgeable people. Cheers; P
icarusSeptember 6th, 2017
thanks will do , I wish i had a cellar to put the water storage tank in but it has to survive outside . At the moment everything connects together with push fit piping and the mains water and high pressure output is in john guest plastic pipe so it is fully demountable The tank presently is right in the middle of the path . I am stripping and re-building the system into a small purpose built shed and putting in some proper trenches so the pipes dont freeze in extreme weather the pump could be run at low speed to circulate water round the system as moving water doesnt get cold enough to freeze . In 2 or 3 weeks time when it is all back together visitors would be welcome . I live in North west Leicestershire . I tend to be a hoarder and dont do tidy- there are quite a few part finished projects in the workshop.Sorry i sent this posting off topic ..On the toilet side i think if i started with the top half of a porta potty toilet added a press button to squirt a measured volume of waterto wet the walls to stop things sticking to the pan and a fine spray hose to clear away reluctant packages . the result would be a sealig trap flushable very low water volume toilet. Its a problem getting enough time to build prototypes to test all these ideas..
Patrick Boylan - September 7th, 2017
Heyup, hate to self promote ! haha but there are a range of pre made composting toilets that you can see here https://www.toiletrevolution.com/composting-toilet/ . This one is the top seller https://www.toiletrevolution.com/products/composting-toilet/separett-villa-9000/ but this one can be connected to a water supply to micro flush the urine channel https://www.toiletrevolution.com/products/composting-toilet/eco-dry/ but that one does need space below the floor for a container. I suspect you’re more inclined to make one yourself – but good to review the existing technology to inform your ideas.
Colin Ives - September 16th, 2017
The UK’s major manufacturer of urine-diverting compost toilets is now Kildwick which is in North Yorkshire. They have a wide range of toilets and components to build your own. You could do with adding them to the main list of compost toilet providers. They offer models similar in functionality to AirHead, NaturesHead and Separett
icarusSeptember 17th, 2017
there are many suppliers but how good is their technical advice?
Ian Barker - November 27th, 2017
We are doing a self build and have planning permission for a straw-bale bungalow with composting toilets and are going through the building control full plans approval process. We have some experience of Humanure Handbook style composting (which has worked well for us), but we plan to build a 2 chamber system under the bathroom built in to the bungalow and vented via the buildings HEV system. Our building control officer seems rather skeptical about composting loos and wants us to adhere to ANSI/NSF 41:2005 (mentioned approved document G) which is an international standard for manufactured composting toilets and not very easy to apply to a one off built system. Having contacted the Environment Agency they have said that we can use composting loos but have said that the “Liquid effluent fraction i.e. urine, needs to be stored in a sealed tank and collected by a waste contractor for disposal at a sewage treatment works.”. Apart from the fact that the urine is the best bit from a plant food point of view we’re worried that once this goes through building control we’ll be digging up half our garden to fit storage tanks. We really want to avoid connecting to mains sewerage if we can – more than 30m away (albeit not much more) – as we’d rather not pay for a high impact lifestyle in order to live a low impact one. We know there are plenty of practical ways to deal with this, some of them outlined in Dave Darby’s book – bale urinals, soak-aways etc. and are very happy we can get something to work various ways from a practical point of view but building control want everything specified to a t and we don’t want to paint ourselves into a corner with the regulations. Can anyone help?
Patrick Boylan - November 27th, 2017
Thanks for the query – the project sounds very interesting. If the building control are looking for NSF certification you can use a Sun Mar or a Clivus Multrum, you can see the NSF listing on this page:
The Clivus Multrum (.co.uk) units are more suite to parks and they are rated as such in x uses per day. The Sun Mar range (available from myself in Toilet Revolution in the UK) are rated in terms of numbers of persons for residential use. I suggest you contact both companies with the numbers of people you are looking to accommodate and see which units are suitable. Both Clivus and Sun Mar are not urine diverting toilets so the urine fraction will have soaked through the compost pile so I would call it ‘compost tea’ as opposed to urine as it will have faecal coliform in it. This will reduce the liquid output though, as much of the urine will soak into the pile, beevaporated off due to warm composting activity, and on electric sun mar units there is a heated evaporation plate to evaporate off excess liquids. It is still advisable to connect up the emergency overflow for power cuts and high usage (say a party for example). It is hard to estimate but even if you have to store excess liquid I would guesstimate for a residential situation that this would be way less than a 1m3 IBC (https://www.deltacontainers.com/reconditioned-ibc/plastic-pallet-reconditioned-ibc-containers.html) which could fit on in most gardens. All that said there are hundreds if not thousands of people in the UK using other technologies like the Separett, AirHead, Kildwik but I suspect they have not had to go through the planning process and they are retro fitting them. Queries welcome
Ian BarkerNovember 29th, 2017
Thanks for the response. That and having a closer look at Multrums has helped me to work through what the Enviroment Agency Regulations are for disposal of compost etc. For anyone else wondering, I think they currently base their policy on ‘Regulatory Position Statement 36’. It tries to shoe-horn compost loos into being either septic tanks or cesspools based on whether the toilet separates “the liquid fraction” from the solids or not. You more or less need them to be in the septic tank category for disposal options. I had read this as: you have to separate the urine, at source as it were. But I think this can just means separating the leachate (‘compost tea’), as with Clivus Multrums (and others I guess).
BTW, buling Regs approved document G4 precludes using power to evaporate off the leachate (as with some Sun Mars) (not that we’d have the power anyway as we plan to be off-grid), but as you say the volumes are small esp. after natural evaporation from the generated heat. Hopefully, we can come up with our own design (with enough leachate storage internally) that will both allow Building control to tick enough boxes and work!
Dave_M - December 3rd, 2017
I’m starting to look into the idea of building a compost toilet and have just finished reading Dave Darbys’ book compost toilets which has encouraged me to continue the idea. I do have two main outstanding questions I’m trying to work through and would appreciate any feedback:
1 – Dog waste – any major concerns with adding this to the mix?
2 – The toilet would be built in an area with coldest temperatures around 15 degrees and warmest around 35 degrees centigrade. Any additional design features that may be useful for warm areas?
The project will start in about 6 months if it goes ahead. Look forward to any feedback, thanks.
Patrick Boylan - December 4th, 2017
With composting high temps are your friend in terms of sanitizing waste. The theory is that bugs etc in human and dog waste are evolved to exist at 37-39 degrees C, body temp for humans and dogs. So nice hot composting temps of 50+ are the business when it comes to killing them off – cool temps are less effective. Here is something i found on the topic https://www.motherearthnews.com/organic-gardening/composting-dog-poop-zmaz84sozraw
Dave_MDecember 5th, 2017
Thanks for the reply, Patrick, I regularly get the (standard) compost bin up to 55-60 degrees C after digging it over, or after fresh addition of material, so hopefully a compost toilet will reach near the same once built.
Most of the information against using dog waste seems scaremongering rather than science, so I’ll go ahead and plan to use that too.
Ann Beirne - September 21st, 2018
This might sound like a stupid question, but I have read some books on compost toilets and I am always amazed to read that you should use a urine separator, I think most people I know do wee and poo at the same time, I do when I do a poo so how the heck can you do separations at these time.
I am very impressed with compost toilets and would like to have and indoor one. My husband and I are very careful not to flush too often especially with the long drought this year.
Looking forward to the explanation
Patrick Boylan - September 21st, 2018
Yes, people do both at the same time. This is no problem using a urine diverting toilet. Basically at the back there is an aperture for solids and at the front there is a funnel for the urine. So, one sits down and does their business and the toilet the separation happens. Indoor versions (like the Separett Villa 9000) have a fan running all time to vents odours so they work really well indoors. Cheers
Helen - October 16th, 2018
Can you have a compost loo for just 2 people or do you need a large amount for it to work well?
Dave Darby - October 16th, 2018
No, a compost loo for two, or even one is fine. The chamber can be smaller the fewer people it serves. Often, they’re ‘mouldering’ toilets rather than true composting toilets.
Nina Wilson - October 16th, 2018
One thing I have been unable to find out from all the sites I have looked at is what capacity do you need? ie. what is the “output” in cubic metres per person for year, allowing for adding scoops of sawdust.
Patrick Boylan - October 16th, 2018
Yes, units for as little as one person are available. A composting toilet, where the waste breaks down to compost inside the unit is always rated in numbers of persons. In the case of the Sun Mar range which has NSF/ANSI 41 certification, the units are independently rated in user numbers. You can view the listing using the link below:
The urine diverting toilet, which does not break the waste down inside the unit can also be suitable for one user. So minimum user numbers is not an issue.
I’m sorry Nina, I do not understand your query. Perhaps it is the user numbers query that is addressed above. The composting toilet is a waste disposal method, rather than a compost producing method although I realise these are sides of the the same coin. The standard (NSF/ ANSI 41) focuses on how many people can use it rather than how much composted material is produces… Hope that helps 🙂
Patrick (Toilet Revolution)
Dave Darby - October 16th, 2018
Nina – I think you might be talking about a self-built toilet? One person produces around 200 litres of faeces per year. Add the same amount of sawdust. But then the whole lot decomposes to about 10% of that volume. Aim for around half a cubic metre per person, and that will be more than enough. It can be used for more than one year then. See our book for more details on self-build – https://www.lowimpact.org/books/books_compost_toilets/
Nina Wilson - October 17th, 2018
Thanks Dave, that was the information I was needing. If you’re using it for compost then you need somewhere to store it until it is ready to go into the garden. So whether you’re using self-build or buying one, you need to know how much space you need to store the stuff.
Patrick Boylan - October 17th, 2018
Just for public information to the forum – Using the bought internal composting toilets, where composting happens inside the product, once the compost comes out of the toilet it is ready to go in the garden (not root veg) as it has broken down in the toilet. This is not the case with urine separating toilets that do not claim to break the waste down inside the product and yes the material must be composted somewhere else. The duration and therefore the volume of storage you need depends on some factors; the type of mulch (we like hemp), hydration, aeration, and if the composting bin is thermally insulated as composting needs 13 Deg C to start. Hot composting is much faster than cold.
Ann - October 18th, 2018
Just wanted to say thanks for the reply about how the separator toilet works, it has put my mind at rest, and we will certainly be looking into getting an indoor compost toilet.
I did try to use the reply button attached to your reply but nothing happened.
Phil Mader-Grayson - July 2nd, 2019
Hi, we run a small campsite and installed compost toilets a few years back. Since then the campers have got used to the idea and now we are collecting more waste than we can cope with on our land. Is there any way we can dispose of this through the council or something? Any ideas would be gratefully recieved.
Dave Darby - July 2nd, 2019
Phil – how much land do you have? Do you have any woodland you can just scatter it around? It will just become part of the soil. Or maybe plant an area of fruit trees, and use it on those? Otherwise, offer it to local growers, or call the council (each council will have different policies).
Ann - July 17th, 2019
Hi We are thinking about providing a compost toilet for our camper van site. It will be a site for one small van only. We do not expect a lot of customers. There is electric hookup for the camper already but no electric where the toilet would be situated. As we are not looking to make a profit we only want to spend minimum amount and also minimum work regarding use of end product/compost.
What would you recommend? I am new to this topic and have zero technical understanding.
Patrick Boylan - July 17th, 2019
based on that info I think this one is most suitable:
Andrew Rollinson - July 18th, 2019
I’d recommend Dave’s book. It is very good read with simple to follow instructions on how to build your own: https://www.lowimpact.org/books/books_compost_toilets/
Shada - July 27th, 2019
I’m thinking of installing a composting toilet into the downstairs washroom , much to the chagrin of the rest of the family! However on reading above, I am concerned as to its acceptability as the room opens into my kitchen / dining room?
Patrick - July 27th, 2019
Thats no worries. The 230v units have a fan running all the time built in, so all odours never get out of the toilet. You could say there are less odours than a normal toilet which dont have fans inside.
Ed - September 24th, 2019
Hi, I’m looking to install a self-build or potentially off-the-shelf (if this helps with my quandry) compost toilet at a new community growing project. It’s currently a blank field (on the outskirts of a residential area) and we’re putting in some polytunnels, a shed and the toilet. The plan is to be off-grid, but on submitting our planning application I’ve been asked to supply a foul drainage report, which basically says I have to connect to the mains sewerage if it’s within 30m. We’re not going to do that because of cost and also ecological considerations. We definitely have enough land to dispose of composted waste and would use the urine on our other compost heaps. Do you know if there is any way round this requirement e.g. the fact it isn’t a residential development and / or environmental considerations being central to our project. I haven’t talked to the planning officer yet, but wanted to understand the issues before I do… any help would be gratefully received! Ed
Patrick Boylan - September 24th, 2019
There are two types of composting toilet. An “internal composting toilet” and a “urine diverting compost toilet”. The internal composting one does not separate solids and liquids and the waste breaks down to compost in the unit which means you never have to deal with raw waste. The urine diverting one separates the solids and the liquids but does not break the solids down to compost in the unit so you have to take out the waste and put it into a composting bin
One from Either category would suit the application:
both non electric and suitable I think. Hope that is help
homeminderuk - January 6th, 2020
Hello, would anyone know if it is possible to convert an ordinary chemical camping type toilet into a composting one? Thanks.
Patrick Boylan - January 7th, 2020
That is an interesting idea. OK, so the chemical toilet (camping or in an RV etc) is essentially a bucket of special liquid. The waste goes into the liquid and the liquid has a property of not allowing the, now, waste solution from smelling. If this was just water the solution of urine and solids would be unbearable. Once the waste goes into the chemical the smells are contained. So can we change this into a composting / waterless toilet. As you know . there are two types of composting toilet. An “internal composting toilet” and a “urine diverting compost toilet”. The internal composting one does not separate solids and liquids and the waste breaks down to compost in the unit which means you never have to deal with raw waste. The urine diverting one separates the solids and the liquids but does not break the solids down to compost in the unit so you have to take out the waste and put it into a composting bin. Changing the chem toilet into an internal composting toilet is not possible as the volume is simply too small to allow the waste to break down, also you would have to create a way of allowing excess fluid (because composting is aerobic and therefore can’t happen in standing / “water” logged matter) out of the composting chamber. But changing it into a very small urine diverting toilet may be possible if you:
1/ placed a urine diversion piece on the top so that solids only go into the container – google urine diverting piece or can use (https://www.toiletrevolution.com/products/composting-toilet/separett-privy-500-kit/?v=d2cb7bbc0d23)
2/ line the container with something – perhaps a compostable bag so that solids can be removed
3/ pipe away the urine into another container
4/ install a 12V fan and flue to take the odours out (if using the toilet inside)
my worry is that you may be better starting with a larger bucket than the camping toilet!! I hope that helps. Thank you
Mike Radcliffe - January 25th, 2020
What are your thoughts on a mid stream collection for composting? I was thinking of creating a system where in the basement you have a 5 gal bucket that is plumbed into the system to strain out liquids right away to the grey collection system for reuse on toliets and irrigation, then solids remain and emptied once per day to the compost heap outside where like what you said it will compost and sit for a year? Thanks
Patrick Boylan - January 25th, 2020
Thats an interesting idea. I don’t have a strong view here so perhaps a quick look at the numbers will help flesh out the idea.
So, you will start with a water supply to drink, shower in etc. On average you will use about 80 litres per person per day (pppd) not including any toilet contribution. So the suggestion here is to take this greywater, filter it using a greywater filter (EG https://www.toiletrevolution.com/products/greywater-filters/biolan-greywater-filter-light/?v=d2cb7bbc0d23) or sedimentation tank and take the clean (ish) water to flush the toilet. Again using average numbers you will then create about 30 litres of sewage per person per day unless you chose an Ultra low flush toilet like (https://www.toiletrevolution.com/products/low-flush-toilets/wostman-eco-flush-low-flush-toilet/?v=d2cb7bbc0d23) where your daily output per person per day would be less than 10 litres pppd. The questions would be:
What is to be done with the remaining 40 litres over a 12 month period? Irrigation in summer for sure
What is to be done with the 10 – 30 litres of sewage per day?
Is the effort in treating the greywater worth saving 10 litres of water per day?
Maybe a waterless toilet would be an option
Hope that helps. happy to keep the chat going with questions and perhaps others will chime in with knowledge and opinion.
Cordelia - February 5th, 2020
I think Patrick raises some good questions. A separating bucket toilet might be simpler to install and need less processing.
Martin - April 18th, 2020
We have been considering an indoor composting toilet to install in our bedroom walk-in cupboard for some time, for the environmental benefits, the lack of plumbing and the fact that our girls are entering their teens & we only have one loo.
My wife has just been put into COVID-19 isolation, so it’s now urgent. Which model would you recommend & why?
Patrick Boylan - April 18th, 2020
There are two types of composting toilet. An “internal composting toilet” and a “urine diverting compost toilet”. The internal composting one does not separate solids and liquids and the waste breaks down to compost in the unit which means you never have to deal with raw waste. The urine diverting one separates the solids and the liquids but does not break the solids down to compost in the unit – you do that outside in a composting bin.
You will need a outlet for a vent which is fan powered
You will need an outlet for the liquid that is not soaked up by the compost
Brands – Sun Mar, Envirolet, Biolet
You will need a outlet for a vent which is fan powered
You will need an outlet for the liquid all the urine
Brands – Simploo, Natures Head, Air Head, Separett
Let me know if I can help more. Thank you Martin
Andrew - May 16th, 2020
What about using “green” biodegradable liners in the bucket to avoid having to wash out and clean the bucket? Can these be safely added to the compost bin?
Patrick Boylan - May 16th, 2020
Yes, indeed. Here is something suitable https://www.all-green.co.uk/catalogsearch/result/?q=30+litre
Martin R - June 8th, 2020
Hi, I’m busy working my way through the online course – very pleased with the amount of good practical advice. 🙂 One suggestion for processing urine is to divert to/pour on to straw bales. Is there something particular about straw or would hay be just as good? I have ready access to old hay bales that we wouldn’t feed to animals. Thanks. Martin
Patrick Boylan - June 8th, 2020
There are two reasons why straw is preferable to hay. Straw is generally cheaper than hay as it isn’t a food for animals. Straw is a by product from cereal crops. The second reason is that straw is more absorbent and is bulkier, this means that it creates natural air spaces so that active composting can happen with the presence of Nitrogen rich urine. Cheers Martin
Martin - June 8th, 2020
Many thanks for your prompt response and for explaining the functional differences between straw and hay. That’s just what I was needing to know, so very helpful. Best regards, Martin
cathie - June 30th, 2020
Hello you great people ? I have a question about my humanure: I’ve got an outdoor compost loo set up in my garden. It’s quite damp due to wee & when I transfer the 20 litre bucket to the humanure bin every few weeks I know it’s a bit too wet. So I’ve been draining off the liquid via a tap on the bottom of the humanure bin [which is actually a large, sealed water butt, with bricks filling the lower 6 inches & a plastic barrier/film, to direct liquid to the tap to try to prevent liquid pooling in the bottom]. The liquid is smelly & dark brown. I’m in an urban area & have no real access to a sewage drain. I tried storing it for a few weeks & then diluting it & using it on the garden as a fertilizer, but I’m a little concerned about doing that again, as it was still very smelly! Last year, my first year, my batch went a bit anaerobic. Once I realised, I drained off the liquid, but it wasn’t smelly at all. I guess cos it’d been sitting in there for a few months? If I drain off the liquid straight away now, to keep the moisture levels right, & then store it [safely!!] for maybe 3 months[?], would it then be ok to use on the garden as a fertiliser? I’m using straw as a soak this year. Used wood shavings last year. It’s just me using it. Only poo, with the inevitable wee, & loo roll. ? Thanks in anticipation of your help. I really love your online content & often share your posts. SUCH great content! 🙂 Peace, Cathie
Patrick Boylan - July 1st, 2020
Hi Cathie, my first instinct is that you could change the soakage material to something more absorbent. Auboise is a good material which (they say) is four times more absorbent than wood chip.
If you still have too much liquid after this (and I don’t really think you should – based on usage by only one person) but if you do; best practice is to store for six months, if you can’t do that add the liquid to another compost pile and if you can’t do that add it to the soil avoiding direct contact with plant life. Cheers
Maren - July 1st, 2020
Hello Cordelia Rowlatt, we loved your compost toilet course. Do you have dimsnions for the urine separater you copied form the Natsol design (you said they were a bit too long and you had shorter ones made, thanks Maren
Cordelia - July 3rd, 2020
The new ones are 270mm from top to bottom and 400mm side to side (the same as the original ones I had made up). There’s a 40mm flat bit along the top with screw holes on the sides – not the middle as they will get peed on. The metal angles out and then curves under. I’m guessing the angle is approx 20 degrees from upright, but not sure. The curve is about 60mm deep and has a little ridge along the edge to direct the urine into the pipe below.
I hope this helps.
Andrew Rollinson - July 3rd, 2020
There was a question asked here in 2017 about getting building warrant verification for urine disposal when a home has a compost toilet. I’m currently in the process of putting an application in for such a system.
I want to build my own, as per Dave’s book, and I’ve already sought out advice from Dave and a few other people. Thank you.
I’m putting together a case. But what I’d really like to know is whether anyone has experience of getting local authority permission for sending the urine direct to a drainage field or soakaway or any evidence-based literature that I could provide to support such a system. I don’t see the need for installing a big plastic underground (septic) tank when there is only urine from a two-person house and maybe greywater.
I know that this depends on percolation rates, etc.
Can anyone help please?
Maria - October 21st, 2020
Hello! First of all, thank you so much for such great content – also the post about using a compost toilet instead of a chemical one in boats and campers! My partner and I are converting a van with the idea of eventually being able to live in it, and we are wanting to build our own compost toilet and use hardwood sawdust as a cover material. After a bit of research, I am not 100% sure if we would want a urine diverter toilet or a fan in it. I was hoping to be able to get a bit of help with this!
We would sometimes be able to compost the contents in his parent’s garden, but other times during longer trips we might have to dispose of them in a general waste bin (I am trying to contact different city councils to see if that’s the best option, but I got the idea from this article: https://www.livesmallridefree.com/blog/where-to-responsibly-empty-your-composting-toilet). I read that Joseph Jenkins doesn’t recommend urine separation for composting, but I was wondering if that would mean the contents would be way too wet to be able to throw them in the general waste bin if we needed to do it.
Does urine separation really affect the composting process? Would it mean we would need to empty our solids container less often than if we didn’t divert it? Also, if we emptied our toilet once or twice a week, would we really need a fan? I have seen that Kildwick offer a toilet without a fan, and Joseph Jenkins doesn’t really use them either.
Thank you very much!
Patrick Boylan - October 22nd, 2020
Hi there Maria,
There are two types of composting toilet. An “internal composting toilet” and a “urine diverting compost toilet”. The internal composting one does not separate solids and liquids and the waste breaks down to compost in the unit which means you never have to deal with raw waste. The urine diverting one separates the solids and the liquids but does not break the solids down to compost in the unit – you do that outside in a composting bin. You could read more here http://www.toiletrevolution.com/news/urine-diverting/
Short story is the reason the diverter doesn’t break down the waste is that it’s too dry. Composting is bacterial and requires moisture. I think Joe Jenkins is basic enough – and not sure he lived in a van.
As for a toilet in van – Yes i think a fan is necessary. Many units are 12V
You have options of internal composting and urine diverting:
Sun Mar Mobile 12 V – from toilet revolution
Air Head – from Woo Woo
Natures Head – google UK dealer
Biolan Simplett – from Toilet revolution
Maybe, Separett, Simploo, Kildwick etc
Yes, composting is affected by the lack of urine. Let me know if I can help more?
Naomi Casserly - December 28th, 2020
We currently have a Biolan Eco for our off-grid cabin in the woods. I love it (and I am the one maintaining it, if you know what I mean). It is an internally composting toilet, so I don’t have to deal with other people’s fresh poo, just lovely compost. We had one or two people staying there all summer and it only filled to about half way. Plus, I love the simplicity of the toilet, there isn’t much to clean, just pour away the wee every few weeks.
I am looking to get another toilet, but they are pricey. Any suggestions?
Does Dave’s book talk about these type of loo?
Just wondering if they are difficult to build; considering you say they are ‘genuinely unique’ in the market. Plus all the stuff about sealing, thermal insulation and making the seep grid.
Patrick Boylan - December 29th, 2020
I’ll leave it up to Dave to clarify what’s in the book as I might have missed some part. I still do think the Biolan Eco is unique in the market and I can’t really comment on what is expensive or not as there is nothing to compare it directly to. But onto the idea of making one yourself – I guess it’s possible but it won’t be free and you’ll have to factor the risk of it not working as well. The key points to the construction are:
Making an insulated body
Making that air tight part from the outlet vent
Making sure the unit tapers off to the end
Outlet at the base for compost removal
Outlet at the base for compost tea liquid
Other things to consider – what materials do you make it with? Perhaps galvanized steel (like duct work) would be workable? Perhaps starting with an insulted composting bin? So the longer I write here the more I’m thinking that I couldn’t make one and I’m also realizing that I’m not adding much help either so time to tap out. Sorry and good luck 🙂
Naomi - January 6th, 2021
Thank you Patrick, much appreciated wisdom.
bill knight - August 16th, 2021
I can see that small quanities of urine can be seperated and disposed of to the ground under EA regs (<10 litres per day). If the toilet serves a house not connected to mains sewerage then how can grey water from showers and sinks be treated to comply with regulations and ? If you have five or six people using a building daily then even if they are low water users this is still a lot of 'dirty' water.
Patrick Boylan - August 16th, 2021
Greywater output is about 80 litres per person per day so you are correct in that there is a lot of water. There are such things as greywater filters:
But there is no legislation requiring you to install them in the UK, unless it sparks the interest of a local authority. People install them to protect the soakaway from clogging up over say 5 years from food and fat / oil.
Hope that helps
Ralph - October 11th, 2021
Patrick from Toilet Revolution claims that ‘urine diverting’ and ‘internal composting’ toilets are two different things, since if you divert the urine, the waste will be too dry to compost. This is interesting because it contrasts with what many other sources say. For example:
“For effective odour-free composting in the UK climate it is essential to divert the urine from the compost chamber.”
From the CAT website
Is this really true? Will urine free waste really not compost down?Doesn’t it depend how much/what soak is used?
Second question: does faeces and toilet paper really breakdown poperly in a plastic container? I always assumed compost needed contact with soil, to give worms and other organisms access..
Patrick Boylan - October 11th, 2021
Thanks for the message and your interest in composting toilets. Here are thoughts on each part of your query:
Is this really true? Will urine free waste really not compost down?
So this question is about urine. Urine provides two things; moisture and Nitrogen. On the moisture side, the function of the small bowl is to remove nutrient from food and the function of the large bowl is to remove moisture from food. This has the result of faeces having a solid structure with limited moisture content, reduced further by the addition of mulch/soak which makes it even drier. So in a urine diverting toilet where all use is seated, the container will not have enough moisture to keep composting going. Maybe the CAT units allow some standing urination and thereforethey do get some moisture.
It is important to note that composting is bacterial life – being single cellular organisms bacteria cannot cope with dehydration; they need moisture to be healthy and perform the composting function. The urine diverting toilets sold by Toilet Rev have small (about 20 litres) containers so size (and therefore time) are also factors that prevent the true breakdown of the waste. The container may be full in a week of use, therefore no composting can be claimed by these units…Maybe the CAT units have larger containers and therefore the material spends longer time inside. But the moisture issue still needs to be resolved.
Doesn’t it depend how much/what soak is used?
No matter what composting toilet you use, they all need mulch so create a good mix. A bigger factor would be to add water to the composting pile.
Second question: does faeces and toilet paper really breakdown properly in a plastic container? I always assumed compost needed contact with soil, to give worms and other organisms access..
Your instincts are correct where you would like the compost pile to be sitting on the ground. Perhaps even open to the air? In this case rain would fall on the composting pile (moisture) and also bacteria and worm already in the soil could access the nutrient in the pile. The problem with this are several issues with open air composting:
1 – Odour
2 – Flies could land and spread contamination onto food for example
3 – If the rain fell on this it could take raw faecal coliform onto the water table and cause disease
4 – Temperature, composting needs 13 Degrees C to start
So, for all these reasons composing of human waste is best done in a insulated bin that has a lid (rain) and a base (rats etc) and of course some moisture can be added to keep the pile moist. Hope those thoughts help 🙂
Ralph - October 11th, 2021
H Patrick, thanks for the response.
Basically I doing some research with a view to making a compost toilet in my garden, used by 1 – 2 people. The 2 main diy ways people to seem to do it are:
1.Poop into a bucket, empty it into a big heap, encourage thermophilic composting. Open to air, rain and ground
2. Poop into a wheelie bin, once it’s full it will breakdown within a year.
Those are 2 very different environments for composting. I’m curious how it works in a more or less sealed plastic container with no worms or other soil organisms. Are air bourne bacteria plus those present in faeces and sawdust all that’s needed? You mentioned size of container: Assuming you get the moisture level right, would you say there’s a minimum size of plastic container you need for the contents to properly breakdown over time?
Dave Darby - October 12th, 2021
We built several compost loos when I was living at Redfield community. One was in the house, on a tiled base, with a hatch, and another was in an outbuilding – the seat was over a wheelie bin. Both had drains at the bottom to let excess urine escape. In both, I added a spadeful of soil – provided all the micro-organisms and mini-beasts required. They both worked perfectly – in that they produced perfect compost. I think you’d have to work quite hard to prevent organic waste from turning into compost – that’s what it wants to do.
Ralph - October 12th, 2021
Great, thanks. Can’t wait to start composting
Omar - November 12th, 2021
Thanks for the course and all the info above in these comments.
I just did Cordelia’s course and I’m planning to install a simple urine-separated bucket toilet system inside my house. We are 2 people living full time in this house. I don’t have space to place a big container under the toilet so the bucket system seems the simplest approach. My plan is to empty the buckets with the solids in a bigger plastic bin (like the 225L Cordelia shows in her videos) and leave it there to compost for a couple of years. However, I still have a couple of questions that I cannot figure out. I’m searching all around but I seem to find different opinions.
1. I’m planning to use around 4 small 20L buckets, so I can keep them aside until I have 3-4 of them full before emptying them into the bigger bin. This way I can delay a bit the procedure of emptying the bucket and do it once every 1-2 months instead of every 2 weeks. But I’m wondering, is this ok? Can they be closed and left aside for 1-2 months or they will dry out?
2. Regarding the 225L bin for the final composting process. I think I understood that Cordelia recommends keeping them for 8-12 months and then drilling some holes in the bottom so they can leach out after the liquid is not toxic anymore. But I don’t understand if we can just keep the bin closed or we need to introduce air in the bin (apart from the moments in which we empty the small buckets). Or do we need to turn it around or remove the content? I see many people go with a compost heap, which I guess has constant access to air and nearby worms and so. What is exactly the agreement on the maintenance when using closed plastic bins?
Thanks for reading and happy composting!
Cordelia Rowlatt - November 14th, 2021
Re: your first question. There’s no reason why you shouldn’t keep four buckets and then empty them all. the older ones might get quite smelly and you might want to keep them outside next to your 220l bin with the lids on but not firmly on so the worms get a bit of air and can keep working, (I always add some compost/worms to a new bucket). If they are in a cool, shady place and the lid is lightly on then they shouldn’t dry out too much. I suggest you try it and see. You can always adapt your methods.
Your second question: I always have some kind of hole/gap/loose lid that allows some airflow. What I have started doing is using a container that already has holes in the bottom from the outset. My thinking is that the amount of stuff leaking out of the bottom will be minimal and the compost benefits from access to all the microbes etc in the soil from the start. I’m still experimenting to see whether the contents will need moving again after emptying the smaller buckets in.
I hope this helps!