An Argument for Ecological Sanitation — “Ecosan”

Ever wonder about the efficiency of our “modern” toilet and water-based sewage systems, or if they even really make sense? Dr. Lucas Dengel shares with us the argument for Ecological Sanitation, or “Ecosan,” from his practice and perspective in Tamil Nadu, India. Ecosan is a universal concept that can (should) be considered everywhere, with practices adapted to local needs and conditions. The transition to a better way of separating, treating and actually gaining benefit from our sewage may be easier said than done, especially in cities—as most common ecosan practices rely on outhouses and composting containers, not conveyance through large, multistory buildings. But it’s time to start shifting our thinking. There’s a real need for healthy sanitation worldwide, and there’s a lot to gain from waste.

The following is reprinted from a document written by Dr. Dengel in January 2011, with minimal edits. Dr. Dengel is a medical doctor who became interested in the prevention of disease, rather than just treatment, early in his career in India. Now an organic farmer and an expert in ecosan, he champions its adoption, along with the use of effective microorganisms (EM) in treating sewage and waste—both for the sake of public health and for their many other benefits. Dr. Dengel lives and works in Auroville, Tamil Nadu, India. 

Dr Dengel with UnBox Fellows

Dr. Lucas Dengel talks ecosan with UnBox Fellows in Auroville, Tamil Nadu, India - Jan 2012

Ecosan – ecological sanitation

Why should there be a need for an alternative to flush sanitation?

A. Flush sanitation

Flush sanitation has some obvious advantages and disadvantages. The biggest advantage is that in the late 19th century, underground sewarage (not flush toilets!) stopped the threat of sewage-related epidemics and pandemics in the (global) North. Another advantage is that, with water being made abundantly available, the technology is definitely user-friendly.

However, disadvantages are obvious and huge:

1) Wasteful use of water resources
Water, mostly of highest quality, is used as a transport medium for human excreta. Flush sanitation requires significant volumes of water, even where flush volumes have been designed to be reduced. (Often in those cases, a single flush is not always efficient enough to obtain a clean toilet.) – See below under Ecosan 3

2) Lack of public hygiene
On coasts and along rivers, sewage is being released into water bodies. The technology package of flush sanitation is not complete if a toilet is not combined with reliable water supply, underground (!) sewerage, sewage treatment (infrastructure plus operations & maintenance (O&M) plus energy needs implied), and treatment (or better, re-use) of sludge. As most systems in the (global) South are incomplete, flush sanitation does not solve the problem of hygienic handling of human excreta, but keeps unhygienic conditions alive and shifts the burden, in general, from the campuses of the rich to the backyards of the poor.

3) Pollution of water cycle
Water bodies, lakes, rivers and seashores are polluted with domestic sewage. Water becomes unusable for most human needs, and water bodies become an eyesore, a source of pest nuisance and breeding sites for disease carriers, instead of being recognized as ecologically indispensable features in the cycle of water. While nature’s water cycle gets polluted, the cycle of elements through soils gets disrupted (shifting nutrients from soil to water bodies), and the soils from where nutrients are being harvested in the form of food crops get impoverished. – See below under Ecosan 5

4) Problems of handling hygiene
Flushing is far from perfectly hygienic: Slow motion films show that huge volumes of fine spray (water with stool particles) get whirled up into the air upon flushing toilets. Working with underground sewer systems has its dangers. Sewer systems and sewage treatment plants require handling of raw or partially treated sewage by humans, exposing them to disease. In order to eliminate the risk of contamination by sewage-borne pathogens, immense protection and technological measures are required. Where protection measures are not provided, a labor force is exposed to pathogens. See below under Ecosan 4

5) Exorbitant costs
The system is expensive: In the North, it has been estimated that 80% of the total costs of sanitation systems are spent on sewerage. It has also been stated that city budgets spend exorbitant sums on the O&M of the systems, up to 30% of their budgets (which is probably the only way to run them reliably). City councils are worried about the state of their 100- to 150-year-old sewer systems; a few city councils seriously discuss a shift to less centralized systems or even to maximally decentralized and water-free systems. – See below under Ecosan 6

6) Waste of biomass and (crop) nutrients
What is called liquid or solid (bio-) waste is a recyclable resource. Flush sanitation, at its best, makes negligible use of recyclable resources or requires additional investment to make use of them. – See below under Ecosan 1

Ecosan outhouses in Musiri, Tamil Nadu, IndiaBasic separation of solid and liquid waste

— Ecosan toilets in Musiri, India; The basic concept of ecosan – the separation of liquid and solid waste for collection and without the need for water to flush

UDDTs - squat and western diagrams

— Basic urine-diversion dehydration toilet (UDDT) designs – squat and western styles

Ecosan toilets in IndiaWestern ecosan toilet

B. Ecosan

Any system of (human excreta) sanitation that aims at saving water and re-use of plant nutrients and biomass may be called ecological sanitation or ecosan, eg. suction toilets on airplanes or waterless urinals. In the following, we speak mainly of urine-diversion dehydration toilets (UDDTs), which allow the re-use of nutrients from human excreta after composting. Dealing in India with “washers,” not “wipers,” we are aware of the need for water for anal cleansing.

The advantages of ecosan/UDDT are as follow:

1) Re-use of biomass and plant nutrients
Human excreta—in particular, urine—contain essential plant nutrients—in particular, the macronutrients that present the bottlenecks of agricultural production, leading to the classic industrially manufactured agrochemicals. These are nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and also some sodium, chloride, etc. The plant nutrients in one person’s excreta (mostly in urine) are sufficient to produce the food required by one person. It is obvious that this cycling of elements in nature should be a source of fertilizers and crop nutrients, and should not be seen as waste.

Human stool provides the bulk of carbon matter in human excreta, as much required for sustainable farming as macro- and micronutrients.

2) Making agriculture and food security more sustainable
The present agriculture scenario is dependent on non-renewable resources (and energy), some of which will be depleted within the next decades. In the case of phosphorus—an element that is essential for every living cell, microbial, vegetal, animan and human—reserves are located in very few countries (Morocco, China, US, Middle East) and estimated to be depleted within 50 to 120 years. Mergers and takeovers amongst multinational mining corporates reflect this knowledge. It is obvious that global food security requires a more reliable resource, such as the excreta of mammals, including man.

The re-use of human excreta as fertilizers and soil conditioners obviously can mean cost savings and benefits for farmers. In practice, it has been observed in Tamil Nadu and Karnataka that as soon as farmers realize the benefits of ecosan “products,” the concept is readily welcomed.

3) Saving water resources
Besides the water required for anal cleansing, UDDT use requires no water. Indeed, the less water that enters the composting chamber, the easier it is kept smell-free.

The average water volume saved by not flushing stools may be in the range of at least seven liters, and for not flushing urine, in the range of two liters saved. If toilet use is complete, the per capita use of water will be in the range or 20–30 liters per day.

4) Improved handling hygiene
In UDDTs, human stool is never touched or handled to complete sanitization, i.e. by desiccation/composting for sufficient time in tropical climates for one year, as per WHO (World Health Organization) standards. Human urine requires zero or minimal precautions, which are easily managed.

5) Avoiding soil and water pollution
With no sewage being produced and released using UDDTs, the risk of spills polluting soils, groundwater, public space and water bodies is minimized.

6) Cost savings
Dispensing with sewers and sewage treatment leads to enormous cost savings in investment as well as in O&M. These savings are so huge that it would be justified to give incentives of several times higher to dry systems than to flush and sewage systems.

7) Feasibility of (total) sanitation
Due to dispensing with sewers and treatment systems, the benefits of sanitation—health benefits, saved expense, improved productivity, etc.—seem to be more readily achievable with ecosan than with flush sanitation, financially as well as technically. A UDDT is a stand-alone system complete in itself. Every UDDT built is a real step toward sanitation, which cannot be said for flush toilets as long as sewage runs through open sewers and/or is not treated sufficiently and/or sewage sludge is not treated adequately.

Disadvantages and challenges of ecosan

At the level of the household, investment costs of a UDDT are higher than those of a flush toilet room. Though as said above, this is probably perfectly balanced by savings in public expense (infrastructure and O&M) on water supply, sewer systems, treatment systems, sludge treatment, energy requirements for water pumps, sewage pumps, treatment systems, etc., and labor expense for sewer systems and treatment systems.

The ideal and user-friendly technology package for urban (middle-class) households (regarding the removal and re-use of urine and compost) in India has yet to be developed. As it it not yet available, it cannot be publicly advertised and is far from being mainstreamed.

The biggest challenge is linking the market—i.e. agriculture—with the production sites—i.e. households, human settlements. Some studies have estimated that the overall costs of this linkage will not be more than the costs of the present transport & disposal system via water, even without taking the cost benefits of the resource into account.

C. Sanitation factors independent of the flush/ecosan issues

Benefits of privacy, dignity, security—in particular for women and girls—are the same for all household toilets, as are benefits of convenience and comfort. These are independent of the type of toilet—flush, dry, composting, etc. Yet these benefits seem to be the most important for the promotion of sanitation.

With the sanitation scenario being framed as an issue for only the lowest end of the socio-economic society strata, there are deficits in thoughtful design and in perfecting execution and finishing. This problem is shared by all efforts in sanitation.

Dr. Lucas Dengel
January 2011

Addition (DF):

Most ecosan toilets in practice today are constructed as outhouses because it’s the most straight-forward way for the system to operate.  Toilets are built above chambers that collect the solid waste, often using two chambers and alternating between them over time—one to use for 12–15 months, and then shifting to the other chamber to let the waste in the first chamber dry and compost.  Ash, lime, sand or sawdust sprinkled on top after each use helps the feces dry, and keeping it dry minimizes the smell.  By the end of 12–15 months, the feces has dried, the pathogens have been killed and the remaining material is rich fertilizer, ready for agricultural use and posing no threat to health.  It is important to keep solid and liquid separate, even for washing afterwards because the wetter the solid waste, the longer it needs to turn to compost and the greater the smell.  Urine is diverted by pipes and, because it is sterile, it can be used immediately as fertilizer for plants, diluted with water or not.  It is often collected in jugs to the side of the outhouse or is sometimes piped through irrigation hoses directly to plants nearby. Access to the solid waste chambers is necessary for removal after composting, and that’s why even when they’re built as rooms in houses, the chambers must have hatches facing outside.

Here’s a brief video about how ecosan toilets are built and how they work—it’s a little awkward at the beginning and geared more towards users than builders, but the animation is good and informative starting about 40 seconds in:

Some additional ingenuity will be needed to create systems for cities and buildings with multiple stories, multiple families or businesses.  The most convenient thing about flush toilets is their ability to transport waste effectively through pipes because of the water used.  Solid waste will require different methods of conveyance and collection services.

Think about all the agricultural nutrients we currently just dispose of, treat and release into our waterways and it’s obvious that it would be better if we could make use of them instead.  Motivation from a more uncomfortable angle is that our land is losing its nutrients because we’re extracting them and not putting them back.  Pretty soon, we’ll face food and agricultural strains and maybe crises as a result.  As Dr. Dengel told us, we’re removing nutrients from our soils and over-supplying our waterways with them, where they do more harm than good (creating algal blooms, feeding bacteria, killing fish and creating dead zones).  We can create a cycle instead of a straight line.  And it’s time to start working on it.


For more on ecosan, effective microorganisms, and a holistic, organic approach to waste and nutrient management, visit Dr. Dengel’s company website, EcoPro.

For more great, comprehensive information (from basics to full details, communication materials and case studies) on UDDTs (urine-diversion desiccation toilets), check out this link on Sustainable Sanitation and Water Managment’s website.

3 thoughts on “An Argument for Ecological Sanitation — “Ecosan”

  1. Amazing work and explaination of the issues at hand. I am a water and sanitation volunteer with the Peace Corps in Peru and we often build Ecosan latrines. Believe it or not it takes a lot of training to create the behavior change needed for correct usage.
    When I return to the states I would be interested in building one in Michigan. How would the winter temperatures affect the process?
    Thanks for all the information! Keep up the good work!

    • Thanks David. I just did a little google digging and found this info:

      “Composting stops below 45 degrees. If the space got colder than that you would need to drain and stop using to prevent freezing. Composting works best when temperatures are 65 degrees.”


      Regarding capacity and temperature together: “Increasing temperature increases capacity between 2 and 3 times for every 10°! Below 50°F composting stops. By insulating bottom and top walls of the composter, using heaters or light bulbs, you can significantly increase capacities. Other ways to increase temperatures include using heat from chimney flues, water pipes, grey water, and solar.”


      It sounds like in whatever way makes most sense, you’d be better off keeping the chambers closer to indoor temperatures than outdoors in a Michigan winter.

      I definitely believe you that it takes a lot of training to create behavior change. That’s the challenge, often even more so than creating the right product. You have to do as much as is needed to persuade people a new way of doing things is actually better, and at the end of the day, it’s really up to them whether or not they agree. Sometimes new products or ways of doing things are too far of a leap from what’s traditional. Or they’re not intuitive enough to be used without extensive training or manuals (and literacy), which is problematic to depend too much on. I’ve been learning a lot more about the field of cookstoves and these are all concerns. These are worthy challenges to keep working on for health and greater benefits, but I sure believe it’s not easy. I bet things get better after peers and neighbors start to adopt new behaviors, then a critical mass can grow and education and encouragement can come from within the community. Glad you’re going through the experience and I hope you’ll share what you learn with others. Keep up the good work, too!

      Would you be willing to write about your experience and some of the challenges and successes you’ve seen to post here on the blog? If so, shoot me an email!

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