So lets begin.
Where?
The toilet is to be built at Can Silo, our land project in Taragonna, Spain. The climate is mediterranean, the land is rocky and is on a westerly slope, leading to areas of flat terraced land. The total land area is just under 5 hectares, with one house on the North East side.
Who for?
The toilet is to be used on a daily basis by my family (myself, my partner Oriol and my 3 year old son Ohli). We occasionally have other family members and friends staying with us, and will be having an increasing number of wwoofers and volunteers over the next few months. From next year we will be holding workshops at the land with groups of possibly 8 or more people, both children and adults. At this time, the most immediate need was for a toilet that would be used daily by 2 1/2 people with the occasional guest.
Physical challenges that needed to be considered
The toilet will need to be close to the house, whilst also being easily accessible from outside. All waste will need to be completely contained for health reasons, and the toilet should be positioned with care for flooding, waste seepage from rainfall, wild animal access points, and consideration for view from the neighbours land and main public road. It will need to be completely accessible for children to use as well as adults and also the elderly.
Restrictions on land
We are renting on a 5 year contract for the property, with the option to stay as long as we like. We arrived here just a few weeks ago, and so it is still very early days, and we can't be sure how long we will choose to be here. I would like to design a toilet system with consideration for this, and reduce the risk of leaving a problem for somebody else who may have no experience with humanure composting to deal with after we have left.
Privacy
I would also like to consider the people owning the neighbouring land, and make sure that we don't put any structures within view of them that may cause unwanted attention and possible smells/flies and things like that. Also for the benefit of those using the toilet, not to place it within a space overlooked by the road coming into the land, and to be aware of placing it so that it is hidden from areas where most activity will take place, eg workshop spaces and the main visitor entrance to the land.
Weather and the elements
In our mediterranean climate it is mostly warm and dry, but during the spring and autumn months there can be some days of very heavy rainfall, with a lot of water falling in a small period of time, with some short term flooding on the lower ground. In the summer, especially July and August, it will be very hot with little or no rainfall. The toilet and inhabitants will therefore need to be sheltered from both heavy rain and strong baking sunlight. There is no water available on site, so any water needed will need to be from rainwater harvesting. At the moment all water is brought in by filling bottles in a local fountain which is very labour intensive.
Financial consideration
We will be using all reclaimed and recycled materials, as we have a budget of round about zero for this project.
Time constraints
We need a functioning toilet as soon as possible, as we are already living on the land. A staged plan would be possible, giving us a working toilet whilst further improvements could be made as time goes on. For maintaining the toilet we would like to design a system that needs minimal input, as we are very busy doing many other things on the land.
Any other needs
We need the toilet to be a simple system, easily understandable for guests of all ages and abilities. It must be safe both as a hygienic system and as a structure. There must be no danger of run off of toilet waste to the house and veg garden. It should be easily and quickly accessible from the house and the most commonly used areas of the land, for my small son and for us, and easily maintained and efficient in process.
And other desires for the toilet
I would like it to be a beautiful space to visit. I would like it to be comfortable to use, and to surprise our family, friends and visitors at how lovely composting toilets can be. I would also love it to be sturdy, well built and long lasting.
The toilet is to be built at Can Silo, our land project in Taragonna, Spain. The climate is mediterranean, the land is rocky and is on a westerly slope, leading to areas of flat terraced land. The total land area is just under 5 hectares, with one house on the North East side.
Who for?
The toilet is to be used on a daily basis by my family (myself, my partner Oriol and my 3 year old son Ohli). We occasionally have other family members and friends staying with us, and will be having an increasing number of wwoofers and volunteers over the next few months. From next year we will be holding workshops at the land with groups of possibly 8 or more people, both children and adults. At this time, the most immediate need was for a toilet that would be used daily by 2 1/2 people with the occasional guest.
Physical challenges that needed to be considered
The toilet will need to be close to the house, whilst also being easily accessible from outside. All waste will need to be completely contained for health reasons, and the toilet should be positioned with care for flooding, waste seepage from rainfall, wild animal access points, and consideration for view from the neighbours land and main public road. It will need to be completely accessible for children to use as well as adults and also the elderly.
Restrictions on land
We are renting on a 5 year contract for the property, with the option to stay as long as we like. We arrived here just a few weeks ago, and so it is still very early days, and we can't be sure how long we will choose to be here. I would like to design a toilet system with consideration for this, and reduce the risk of leaving a problem for somebody else who may have no experience with humanure composting to deal with after we have left.
Privacy
I would also like to consider the people owning the neighbouring land, and make sure that we don't put any structures within view of them that may cause unwanted attention and possible smells/flies and things like that. Also for the benefit of those using the toilet, not to place it within a space overlooked by the road coming into the land, and to be aware of placing it so that it is hidden from areas where most activity will take place, eg workshop spaces and the main visitor entrance to the land.
Weather and the elements
In our mediterranean climate it is mostly warm and dry, but during the spring and autumn months there can be some days of very heavy rainfall, with a lot of water falling in a small period of time, with some short term flooding on the lower ground. In the summer, especially July and August, it will be very hot with little or no rainfall. The toilet and inhabitants will therefore need to be sheltered from both heavy rain and strong baking sunlight. There is no water available on site, so any water needed will need to be from rainwater harvesting. At the moment all water is brought in by filling bottles in a local fountain which is very labour intensive.
Financial consideration
We will be using all reclaimed and recycled materials, as we have a budget of round about zero for this project.
Time constraints
We need a functioning toilet as soon as possible, as we are already living on the land. A staged plan would be possible, giving us a working toilet whilst further improvements could be made as time goes on. For maintaining the toilet we would like to design a system that needs minimal input, as we are very busy doing many other things on the land.
Any other needs
We need the toilet to be a simple system, easily understandable for guests of all ages and abilities. It must be safe both as a hygienic system and as a structure. There must be no danger of run off of toilet waste to the house and veg garden. It should be easily and quickly accessible from the house and the most commonly used areas of the land, for my small son and for us, and easily maintained and efficient in process.
And other desires for the toilet
I would like it to be a beautiful space to visit. I would like it to be comfortable to use, and to surprise our family, friends and visitors at how lovely composting toilets can be. I would also love it to be sturdy, well built and long lasting.
As a long time wwoofer and traveller I have come across quite a few composting toilets in my time. Some of them have been amazing wonders and a joy to behold, others have been a bit of a horror movie, something like an Indiana Jones adventure where maggots, beetles and rotting waste come within just a few centimetres of your bare bottom. I thought it would be useful for me to look back at what I have seen before, and combine this with some more research into other alternatives, to get a wider idea of the possibilities. Below are some images and details of what I found.
Preliminary observations
I have observed in the past that there seemed to be two main types of simple composting toilet systems that I have had experience with and are quite straightforward to make.
The big drop
In this system a large hole or sealed container is created, and the toilet seat built on top. As the space is large it takes a long time to fill - in many systems (such as this one in the Panya project in Thailand) it can be up to a year or more. This toilet in the picture is designed that when it is full the cob structure can be broken on the side at ground level to release the waste from the bottom, hopefully coming out as compost. It can then be re sealed and used again. An exhaust pipe is added to try and release any bad smells.
The waste is mixed with carbon material, (such as rice husks or wood shavings) to maintain a balance of nitrogen and carbon, and to help the waste break down most efficiently and successfully. When the container is full, if it is a hole in the ground the toilet structure is simply moved off the top and placed over a new hole, whilst the full hole can be filled in, ideally planting a tree into the hole to make the most of the nutrients in the waste. This is a great system if you are reforesting the land, which is what one of my neighbours is doing. I've uploaded a booklet explaining how to use this method on the appendix page of this project.
In this system a large hole or sealed container is created, and the toilet seat built on top. As the space is large it takes a long time to fill - in many systems (such as this one in the Panya project in Thailand) it can be up to a year or more. This toilet in the picture is designed that when it is full the cob structure can be broken on the side at ground level to release the waste from the bottom, hopefully coming out as compost. It can then be re sealed and used again. An exhaust pipe is added to try and release any bad smells.
The waste is mixed with carbon material, (such as rice husks or wood shavings) to maintain a balance of nitrogen and carbon, and to help the waste break down most efficiently and successfully. When the container is full, if it is a hole in the ground the toilet structure is simply moved off the top and placed over a new hole, whilst the full hole can be filled in, ideally planting a tree into the hole to make the most of the nutrients in the waste. This is a great system if you are reforesting the land, which is what one of my neighbours is doing. I've uploaded a booklet explaining how to use this method on the appendix page of this project.
If the structure was built above ground often two are built side by side, and when one side is filled the top is simply sealed up and the seat moved to the second side. During the next year, whilst the second side is being filled up, the first side should be composting down nicely, and if the balance of human waste and brown woody material was right, then by the end of the second year (when the second side has been filled) the first one can be opened and the manure emptied to be used in the garden. I have seen these systems working at different communities in the UK and in Asia, and mostly successfully. I have however sometimes come across the problem that when the chambers are opened after one year of composting, the waste hasn't been completely broken down. And because the chamber was sealed with no access or view over the year this isn't apparent until completely opened, which is a pretty nasty thing to discover when dealing with such a huge pile of human waste. And depending on the design it can also be difficult to seal up again once opened. Depending on the conditions it can take a lot longer than one year to break down fully, and so both chambers can sometimes fill up before you are able to empty them, leaving you with no toilet space. This image is also from the Panya project in Thailand. Although incredibly beautiful, this toilet block suffered from bad smells, non rotted down manure after opening the chambers, and I found it to be also dangerous for children, after 2 year old Ohli struggled with the squatting toilet design and one day had a lucky escape after almost falling into the large waste chamber underneath. It was however very practical for the large number of volunteers that came through this community, and could store a lot of waste without needing any regular maintenance or attention.
The bucket and heap
This is one method explained in detail in The Humanure handbook, by Joseph Jenkins, one of my research books. In it's most basic form, it is a toilet seat on top of a bucket. After using the toilet the human waste is covered with some woody brown (carbon) material, (such as woodshavings or sawdust) and when it is full the bucket is emptied onto a seperate compost heap, and again covered with carbon materials as needed, as mulch on the top. A structure can be built around the bucket to make it as fancy or simple as you please. The benefits of this system are that it is very small and portable, you don't need to build any large structures to house the toilet (apart from the seperate compost heap in a different location) so you can put it anywhere you like. It's also very easy and quick to build and can be a very simple design. One main challenge with this would have to be that it does need regular attention - Joseph Jenkins reckons that for a family of four the bucket will probably need to be changed about once a week. For a large amount of guests he suggests using several buckets that can be sealed with a lid and changed over once full, and then all emptied at the same time, so being as time and energy efficient as possible. Although the waste should always be covered with mulch and not visible, when you empty the buckets you are having a closer contact with the waste than with the other systems.
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The advantage of having an open design compost heap is that you can keep a check on the break down process, and manage any bad smells or imbalances that may arise as you can have total access to the compost heap if you need it. If more carbon material is needed then you can see that much more clearly than if it's in a sealed container and it is much more likely to break down properly.
These are some images of the compost heap suggested by The Humanure Handbook to go with the bucket method. There are three sections; one either side for the manure - after one is filled it is left to break down and compost whilst the second is filled. And the section in the middle is to store mulch to cover the waste after it is added, so that flies aren't attracted and there are no bad smells. The centre also has a roof to stop the rain from destroying the mulch material. Rainwater can also be collected from this roof to use for washing out the buckets, as you can see in the last image. |
These are not the only composting toilet methods, but in the early stages of this design they were the two that I had most experience with. You can see more designs in the Evaluation and Tweaks section of this project, where my observations into toilets have been expanded.
And just how safe is the compost to use?
Of course one of the main desires of creating a compost toilet is the production of good, safe, clean, nutrient rich compost. Most common worries with composting human waste is that it can spread virus, bacteria and worms throughout the garden, and potentially lead to some severe health problems. It is something we are mostly very unfamiliar with so these concerns do have to be looked at. These are quotes directly on this matter from Joseph Jenkins;
"Lettuce and radishes in Ohio sprayed with sewage inoculated with Poliovirus I showed a 99% reduction in pathogens after six days; 100% were eliminated after 36 days. Radishes grown outdoors in soil fertilized with fresh typhoid-contaminated faeces four days after planting showed a pathogen survival period of less than 24 days. Tomatoes and lettuce contaminated with a suspension of roundworm eggs showed a 99% reduction in eggs in 19 days and a 100% reduction in four weeks. These tests indicate that if there is any doubt about pathogen contamination of compost, the compost should be applied to long-season crops at the time of planting so that sufficient time ensues for the pathogens to die before harvest."
From this it seems that even if the crops are sprayed directly with pathogens they don't survive for very long after being out in the open. But to exercise caution in using compost possibly containing pathogens, making sure that it is only on crops not to be harvested in a short period of time.
This doesn't really apply to composting toilet systems though, as this is talking about directly applying pathogens, not composting them first. By using a well functioning composting method, these pathogens should be completely killed, leaving the finished compost completely safe and pathogen free.
"WELL-MANAGED THERMOPHILIC COMPOSTING SYSTEMS
Complete pathogen destruction is guaranteed by arriving at a temperature of 62C (143.6F) for one hour, 50C (122F) for one day, 46C (114.8F) for one week or 43C (109.4F) for one month. It appears that no excreted pathogen can survive a temperature of 65C (149F) for more than a few minutes. A compost pile containing entrapped oxygen may rapidly rise to a temperature of 55C (131F) or above, or will maintain a temperature hot enough for a long enough period of time to destroy human pathogens beyond a detectable level."
"According to Feachem et al., a minimum retention time of three months produces a compost free of all pathogens except possibly some intestinal worm eggs. The compost obtained from these types of toilets can theoretically be composted again in a thermophilic pile and rendered suitable for food gardens. Otherwise, the compost can be moved to an outdoor compost bin, layered and covered with straw (or other bulky organic material such as weeds or leaf mould), moistened, and left to age for an additional year or two in order to destroy any possible lingering pathogens. Microbial activity and earthworms will aid in the sanitation of the compost over time.
(From The Humanure Handbook)
So we can choose to one of several ways to ensure safe compost: by maintaining a thermophilic hot pile and monitoring the temperature to destroy the pathogens, by building up a normal, unchecked cold compost pile and then re-processing it thermophilically in a hot pile before use, or by building up the compost in a regular unchecked compost heap and then leaving it for an additional year or two to make it completely safe.
(For more comprehensive information on thermophillic bacteria, composting stages and the sanitation of compost, you can link to a very detailed explanation here)
"Lettuce and radishes in Ohio sprayed with sewage inoculated with Poliovirus I showed a 99% reduction in pathogens after six days; 100% were eliminated after 36 days. Radishes grown outdoors in soil fertilized with fresh typhoid-contaminated faeces four days after planting showed a pathogen survival period of less than 24 days. Tomatoes and lettuce contaminated with a suspension of roundworm eggs showed a 99% reduction in eggs in 19 days and a 100% reduction in four weeks. These tests indicate that if there is any doubt about pathogen contamination of compost, the compost should be applied to long-season crops at the time of planting so that sufficient time ensues for the pathogens to die before harvest."
From this it seems that even if the crops are sprayed directly with pathogens they don't survive for very long after being out in the open. But to exercise caution in using compost possibly containing pathogens, making sure that it is only on crops not to be harvested in a short period of time.
This doesn't really apply to composting toilet systems though, as this is talking about directly applying pathogens, not composting them first. By using a well functioning composting method, these pathogens should be completely killed, leaving the finished compost completely safe and pathogen free.
"WELL-MANAGED THERMOPHILIC COMPOSTING SYSTEMS
Complete pathogen destruction is guaranteed by arriving at a temperature of 62C (143.6F) for one hour, 50C (122F) for one day, 46C (114.8F) for one week or 43C (109.4F) for one month. It appears that no excreted pathogen can survive a temperature of 65C (149F) for more than a few minutes. A compost pile containing entrapped oxygen may rapidly rise to a temperature of 55C (131F) or above, or will maintain a temperature hot enough for a long enough period of time to destroy human pathogens beyond a detectable level."
"According to Feachem et al., a minimum retention time of three months produces a compost free of all pathogens except possibly some intestinal worm eggs. The compost obtained from these types of toilets can theoretically be composted again in a thermophilic pile and rendered suitable for food gardens. Otherwise, the compost can be moved to an outdoor compost bin, layered and covered with straw (or other bulky organic material such as weeds or leaf mould), moistened, and left to age for an additional year or two in order to destroy any possible lingering pathogens. Microbial activity and earthworms will aid in the sanitation of the compost over time.
(From The Humanure Handbook)
So we can choose to one of several ways to ensure safe compost: by maintaining a thermophilic hot pile and monitoring the temperature to destroy the pathogens, by building up a normal, unchecked cold compost pile and then re-processing it thermophilically in a hot pile before use, or by building up the compost in a regular unchecked compost heap and then leaving it for an additional year or two to make it completely safe.
(For more comprehensive information on thermophillic bacteria, composting stages and the sanitation of compost, you can link to a very detailed explanation here)
Living within the ethics of permaculture
Finding a safe and sustainable way to deal with human waste is a great way to bring the ethics of permaculture design into one element of our lives that is often overlooked by the majority of people. When considering Earth care, the standard process of flushing away material that is full of nutrients that can benefit the soil is just so wasteful. We can easily put this resource back into the soil from where it originally came, from the plants that fed us in the first place. This in turn then increases soil fertility, which helps plants to grow. So simple, just as nature intended.
Looking at the other principles of People care and Fair shares, it is very irresponsible to be using fresh water in this way when so many around the world don't even have enough to survive. To flush our waste away into clean, fresh drinking water is a very poor use of a limited resource on Earth. Thinking of our future generations, this is a resource that will most likely be becoming more and more scarce as time goes on. Using compost toilet systems means that we aren't using more than our fair share of water in this way, and we are helping towards securing our water resources for others that need it more, and for the future.
Looking at the other principles of People care and Fair shares, it is very irresponsible to be using fresh water in this way when so many around the world don't even have enough to survive. To flush our waste away into clean, fresh drinking water is a very poor use of a limited resource on Earth. Thinking of our future generations, this is a resource that will most likely be becoming more and more scarce as time goes on. Using compost toilet systems means that we aren't using more than our fair share of water in this way, and we are helping towards securing our water resources for others that need it more, and for the future.
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