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Dry Toilets
Why Use Dry Toilets ?

Our Relation to our Dejecta

Three Generations of Dry Toilets

The BLT Instruction Manual
Chemical Composition of Human Dejecta
Composting Human Dejecta
BLT's on the Market
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To find out how to build your biolitter toilet, click here, or download the pdf schematic. [Drawings adapted by Olivier Vienne, from Écaussine in Belgium]

The text within this page was first published in French on in 2003

The original text has been adapted and translated by André Leguerrier. First published on this page at : 2009-06-15

Last update : 2016-02-21

Three Generations of Dry Toilets

First-generation toilets were the latrines or backhouses of our grandparents: a simple hole or pit in the ground, above which there was a floor or board with a hole, with or without a proper seat. These toilets were smelly and very polluting due to anaerobic fermentation (absence of air). Agricultural reuse of the effluent did not however seem to present a major problem. This was current practice for centuries, indeed millennia.

Second-generation toilets developed in the 20th century are mainly characterized as source-separating Scandinavian-type toilets. They aimed at the outset to improve dry toilets' convenience. In fact, they constitute a technical improvement on the traditional chamber pot to make dry toilet use possible within the home, similarly to water closets. To minimize the frequency of the required emptying of the waste, urine is first separated from the faeces: this is the toilet's most important characteristic. Urine, which represents about 90 % of the excreta, is diverted to a separate storage tank while the faeces are collected in a main compartment. To reduce their volume, these are usually dried with a heating element, a hot air current or solar energy. A forced air ventilation system is usually provided to control odours that ultimately appear after waste separation. The ventilation system almost always works electrically. The dried faeces and the urine are then commonly used in the garden and/or for agricultural use. To avoid burning plants, urine must first be diluted to 8 times its volume.

Third-generation toilets differ from the others on how they work, biologically. Smell is inhibited thanks to the addition of a litter composed of plant matter that is rich in cellulose. This is the basis of the biolitter toilet or BLT. In this toilet, plant cellulose biologically inhibits the enzymatic reactions in the excreta that are responsible for the odours. This can only work in the presence of urine. To prevent anaerobic fermentation (with the consequent odours), the toilet's «receiving» capacity cannot be expected to exceed the volume of one week's «production». Therefore, the emptying of the container is more frequent. Note that a BLT, even though it is placed within the home, does not require mechanical ventilation. Before reuse for agricultural or gardening purposes, the BLT's effluent must be composted in a two-stage process, over a two-year period. The compost thus obtained is suitable for all plants, without any health risk.

The Biolitter Toilet or BLT

Not so long ago, I was annoyed to observe that people reduced my overall thinking to the sole biolitter toilet – pejoratively called a « cat litter box » by some – of which I was said to be the inventor. Now, « invention » is a big word for something which's time was long overdue. It now appears I was not the only proponent of this type of toilet, at about the same period in time [1]. It's true that I was the first to launch the biolitter toilet in Europe, mainly France and Belgium (and eventually my native Hungary) under the name « toilette à litière biomaîtrisée » which translates as a biocontrolled litter toilet. The launch came in 1992, after about 10 years of personal use at home as well as laboratory testing, more than 20 years after my first tinkering with dry toilets. To my credit, I simply provided the scientific explanation to how odours are controlled, and I proposed the biological means of returning our dejecta back into nature's great natural cycles. Nevertheless, I claim the authorship of the name « toilette à litière biomaîtrisée » known in short as the TLB in francophone Europe (now known as the BLT in English). The name came to me in 1995 during a symposium organized by the « Ecole d'Agriculture de Ath » (Ath Agriculture School) in Belgium where many speakers presented case studies of worldwide experiments on livestock quality in production facilities where livestock was raised in biocontrolled-litter housing systems (better known as deep-litter or deep-bedding housing systems in the English-speaking world). It became obvious to me that the lack of odours in these facilities was based on the same principles as those applying to the litter toilet that I had launched 5 to 6 years previous. Before 1990, practically no one in the French-speaking world seemed interested in dry toilets. I believe I was among the first scientists (if not THE first) to actively and publicly promote these toilets (via conferences and lectures, documentaries and interviews), and to research the scientific aspects of odour control by the use of cellulose litter. My first conferences on the subject provoked outright laughter : at the start of the 1990's, no one, absolutely no one, took me seriously.

Joseph JENKINS, The Humanure Handbook : A Guide to Composting Human Manure, 1st published in 1994, 3rd edition in 2005

Since then, the rise of water problems has helped change attitudes towards dry toilets. The number of websites devoted to the subject is inexhaustible. Unfortunately, there is a tendency to consider all dry toilets as equal to the BLT. Any toilet that does not involve the use of water to evacuate excreta is defined as a « dry toilet ». This is a vast category that covers set-ups or systems that are sometimes even more polluting that flush toilets. To call the biolitter toilet a « dry toilet » will tend to confuse the issue, between a toilet that is truly respectful of the biosphere, and all those others that are less environmentally friendly, if not outright un-ecological.

In the English-speaking world, the third-generation toilet I promote is better known as a «sawdust toilet», a term popularized by another proponent of such toilets, the American Joseph Jenkins. The term itself is somewhat restrictive, since sawdust is only one of the possibilities available as a litter cover material [2]. I prefer the term «biolitter toilet» (simpler than «biocontrolled litter toilet»), which calls to mind the litter's biological action in the toilet's modus operandi, similar to the French version term I coined in 1995 (toilette à litière biomaîtrisée) and that is currently used in French-speaking Europe.

In his book, Joseph Jenkins describes the sawdust's ideal characteristics, and if sawdust is somewhat limitative per se, his «recipe» of non-kiln dried sawdust apparently works quite well. I now understand that he has shifted away from the term «sawdust toilet» and is promoting the term «Humanure toilet», as he too uses a variety of litter materials other than sawdust. On the question of sawdust, I personally have tried many kinds of sawdust : from softwood, hardwood, exotic wood, treated wood, finely or coarsely ground sawdust, etc. In all cases, without exception, the compost and even the toilet had a tendency to become smelly due to the lack of aeration. Some women complained to me about the dust in the toilet. As for sawdust from exotic tropical wood species, obnoxious smells eventually appeared, due to these species' essential oils. I have even tried hemp, which doesn't work well to control odours. A mixture of sawdust with wood shavings (non tropical) is the best.

Esperanto-speaking people have a proper term : the «pajlaĝnecesejo», although I prefer the term «pajlaĝejo» (the seat with litter). In Hungary, the toilet is suitably called «alomszék» (or litter toilet).

Finally, it appears that the Finns seem to have started considering the biolitter toilet, although the image of their toilet is somewhat ambiguous. The litter container and ladle are typical BLT accessories. However, as a BLT doesn’t generate odours like a conventional flush toilet, one wonders why an aeration pipe is included, as it is really only necessary in conventional source-separating dry toilets. Up to now, the latter have been the only kind of dry toilets used in Scandinavian countries. Old habits seem to be hard to get over.

Who Uses the BLT

Once you recognize that continued use of flush toilets is leading us to an environmental dead end, you can thenceforth consider switching to a BLT, as has been done by thousands of households in Belgium, France and other European countries since my public interventions. (I have no doubt that a similar phenomenon has also occurred in North America since the publication of Joseph Jenkins' book [1].) A survey that was carried out [3] revealed that families having adopted the BLT no longer want to have anything to do with conventional WC's, feeling that the BLT provides comparable convenience while satisfying their environmental concerns. The survey also confirmed that BLT use was not exclusive to those with « back-to-the-earth » or other fringe lifestyles. In fact, the majority of users have a college degree or equivalent, sometimes living in upscale homes or at the least in very comfortable ones.

Christine ROUSSEAU, Toilette à litière biomaîtrisée : psychologie et motivation. (The biocontrolled litter toilet : psychology and motivation) Final thesis, Institution d'Enseignement de Promotion Sociale de la Commission Française de Peruwelz 1996.

It is noteworthy to add that the biolitter toilet also applies to animals. Livestock raising in organic deep-litter housing systems is a proven technique that produces high-quality meat. By composting the litter-bedding over which livestock is raised, we now have the means of preventing water pollution caused by liquid pig manure. Should we not convince pig farmers of the soundness of this approach?

How the BLT Works

A purpose of the BLT is to restore our dejecta into the process of humus formation under the best possible conditions. For this, we must first prevent urease – an enzyme in our excreta – from transforming precious organic nitrogen into ammonia, unusable for humus synthesis. This phenomenon was first understood thanks to laboratory observations [4] : that plant cellulose inhibits the enzymatic reactions that mineralize dejecta's organic matter. Now, these reactions constitute the origin of obnoxious smells. An idea became obvious : add plant cellulose to our dejecta in order to block enzymatic reactions, and in so doing, prevent odours. Another benefit of this gesture is to increase our dejecta's carbon / nitrogen ratio to a level that is ideal for exterior aerobic composting. [5].

Réf.: NIMENYA H., et coll., Ann. Méd. Vét., vol. 143, pp. 409-414 (1999)
Our dejecta's C/N ratio is about 7, whereas that of plants is between 200 and 300. To start composting, the C/N ratio should be around 60. Combining animal-sourced nitrogen (dejecta) and plant carbon (the litter) creates the ideal conditions for humus formation, without unpleasant odours.

An important detail: the inhibition of enzymatic reactions can only take place in a moist environment, therefore in the presence of urine. This is the reason you must absolutely not separate urine from faeces. Another important detail : the introduction of plant cellulose in the BLT's process (i.e. the litter) must occur immediately after defecation or urination, to prevent the start-up of mineralization.

What the BLT Looks Like

Once you have adopted a BLT, you don't need to attempt to imitate conventional WC's, unlike what most commercially-sold dry toilets do. It's no longer necessary. You can design a beautiful piece of furniture which's style can match that of the rest of the home. You can apply the same principle to a biolitter urinal.

Technically, simplicity is of the essence. The BLT is a simple receptacle placed within a piece of furniture that can evoke a simple chair with a hole in the middle. Important detail : a protective baffle must be mounted under the cover, unless your litter receptacle rests up against the underside of the toilet seat. For added comfort, you can even add armrests and upholstering. You need not provide water supply (except for a lavatory), nor a drain, nor mechanical venting for the BLT. The BLT can be placed within the home, in either the toilet room or bathroom. For added convenience, some even put a BLT in the guest bedroom, behind a folding screen. It is also quite appropriate for a sickroom. Also, it is important to provide a litter container, either separate from the BLT or integrated in the BLT design.

When used as recommended, the BLT does not generate more odours than a conventional WC.

Finally, you can make your own litter, as long as you have a proper garden shredder. Dead leaves, wood trimmings, ligneous plant stems like sunflower, green pepper, lavender, etc., make an excellent toilet litter. Shredded cardboard and dried grass clippings can also be used.

In all cases, it's better to store your litter in a protected area, especially when you make it yourself. To see a litter storage bin, click here.

Plastic or Metal Receptacle

For a good BLT, I have always recommended a stainless steel bucket . It's a bit more expensive (between 60 and 100 € for a 15 to 18 litres capacity) but so much easier to clean and maintain.

An enamelled metal bucket works well and costs much less than stainless steel. Cleaning and maintenance are also easy. However, these buckets may be hard to find and don't necessarily come in all sizes. In Belgium for example, I have only found 12 litre buckets, which require more frequent emptying. On the other hand, they are lighter to handle…

Galvanized steel buckets are also convenient, but they always end up rusting. The bucket quickly becomes unusable.

Plastic buckets are inexpensive, but they take up odours with long-term use. A BLT equipped with this bucket always ends up smelling bad, even with rigorous cleaning. Plastic is the cheap solution, in price, but also in quality. There exists a trick however to reduce the odour problem and extend a plastic bucket's lifespan. You need 2 or 3 buckets per toilet. While one is « in service », the other(s) is(are) put outside, filled with soapy water or with a water mixture containing sifted clay powder. This water can be reused often. Place the buckets in the shade, as the sun's UV makes plastic fragile.

Important: A BLT Must Be Beautiful!

In most homes, entering a water closet constitutes a discontinuity in home decoration. You pass from rooms furnished with a certain style to enter an impersonal cubbyhole, confronted to a porcelain toilet that is totally unrelated in style to the rest of the home.

The BLT's design can and should be integrated to the furnishing or home decorating style . You need two pieces of furniture (the toilet and the litter container ) in similar style as your other furniture. In a tasteful décor, the BLT can become a woodwork masterpiece that can even be installed in a sickroom, behind a folding screen in a guest room, and so on. It provides a comfort that requires no major and costly transformations to install plumbing. All styles are adaptable to a BLT (baroque, gothic, colonial, modern, etc.). I have seen BLT's built in a local folk style . These can be richly decorated with paintings or carefully sculpted. An interesting option is a throne style sculpted and cushioned chair with armrests . When the BLT is placed in the bathroom , its case can be tiled as the rest of the room, or not .

How to Build your BLT

The BLT does not benefit from any commercial advertising. The basic idea is that anyone and everyone should have access to a toilet that is truly environmentally friendly. It can obviously be built by your average handymen or «do-it-yourselfers» using the plans provided within this website. You may also want to look-up Joseph Jenkins' drawings and sketches in his book on sawdust toilets. Here is a finished example.

An elegant solution can also consist in setting a sanitary bucket in a chair seat : an inexpensive and efficient solution, and very presentable.

However, if you are not handy with tools, you can find BLT's already available on the market in some regions of the world. This is particularly true in France and Belgium, where the EAUTARCIE website has had considerable success. One can only hope that BLT manufacturers will sprout worldwide.

BLT's for Collective Use

The BLT is perfectly adapted to grouped collective set-ups, as for festivalsand concerts. . However, there are certain needed precautions to avoid eventual failure. Such set-ups require added supervision when compared to WC's. A person must be ever-present to ensure litter and toilet paper supply, but also to remove and replace the filled-up buckets in proper time. For this purpose, each toilet should be assigned 2 or 3 containers for temporary containment to provide extra time between actual waste removals. The waste can be dumped in a container that then needs to be transported to a proper composting facility. The collective set-up can even include biolitter urinals.

An Alternative to the BLT?

Considering the explanations provided under « How to use a BLT in a city apartment? », after close to a century of flush toilet domination, the convenience of these will certainly be hard to give up for many, if not most people in our modern world. As for high-density housing such as city apartment buildings, dry toilets are practically impossible to implement. Even in rural and peri-urban areas, adopting biolitter-type dry toilets is a challenge. Fortunately, there is a means of implementing sustainable wastewater management by applying the principles of EAUTARCIE’s version of ECOSAN (SAINECO), without the need to change the flush toilet concept. It only requires to replace standard full-flush toilets by low-flow toilets [6], and drain these to individual or collective septic holding tanks. Thereafter, toilet effluent would be collected by municipalities and conveyed to treatment centres for composting under the biolitter toilet principle.

Ideally (although not absolutely essential), such toilets would be high-efficiency low-flow toilets (i.e. very water-wise), as the biolitter toilet principle works best when human dejecta are diluted as little as possible in order to facilitate subsequent treatment (composting) of the black water. Such high-efficiency toilets, which we will call turbo-toilets or TT's, could resemble those of boats, buses, trains and airplanes. After use, the stainless steel or porcelain bowl would be rinced with a high-pressure jet of water by which very little water would be used.

An inherent condition for a TT would be that the concentrated toilet effluent be easily transportable to the septic holding tank via a network of pipes. Therefore, toilet effluent is to be liquefied into a slurry with the help of a pulverisor (or grinder) and injected under low pressure into the pipes. Toilets equipped with grinders already exist (although they are not called « turbo-toilets »), but they usually come with a standard volume flush, which represents much too much water. It's to reduce this water volume that the water flush must be pressurized. High-efficiency low-flow toilets are already used on boats, and could qualify as TTs.

To continue reading, go to The BLT Instruction Manual


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