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Need for evolution in design for appropriate sanitation

Shrikant Navrekar, Hon. Training Director at Nirmal Gram Nirman Kendra, Nasik, India

Pit Toilet is the commonest type of toilet adopted under sanitation programs world over especially in developing countries. Looking at its merits like low cost, less water requirement, easy maintenance etc, it is the most suitable type for situations in developing countries. As a single toilet it is perhaps the best & user-friendly toilet. However when it comes to large scale adoption of this type, some issues emerge which need to be addressed very carefully. Observations from the field show that pit toilets are showing some red signals on issues like ground water safety. Other issues which need urgent attention are rodent menace, hollowing of ground due to increasing density of pit toilets, removal & use of pit contents (manure) particularly in single pit toilet, non availability of specialized pan & trap etc. These observations may differ a little from country to country. Hence a global review of this technology is essential.

Ground water safety parameters

It is generally advised that a particular distance be kept between the leach pit and the water source. However, it is practically very difficult to do it in many places especially in water affluent areas. The norm is compromised and a toilet is constructed in the vicinity of the water source in areas, where hand pumps are abundant. In this case, there is not enough space beyond the permissible safe distance.

Similarly in densely located households (which is a common scene in Indian subcontinent), it is again practically difficult to construct a pit toilet which would permit easy access and at the same time maintain safe distance. This is particularly difficult when each house is intended to be provided with a toilet. Now the issues of concern are:

i) How can one recommend and expect adoption of safety measures in above situations?

ii) Are wrongly located toilets going to pose a threat to human health by way of water pollution and should these be abandoned?

iii) In rainy season, soil gets saturated with water & the water in subsurface area practically gets mixed. It is also hard to predict the water currents in such conditions. In such condition, it is likely that the water in subsurface area in that location is fully mixed with human excreta. Do the water safety measures have any meaning in rainy season? (again particularly in dense locations).

Popularization of toilets also increases the density of toilets. Having 10 toilets in a given area certainly differs from having 100 toilets in the same area. What is the difference in these two situations with reference to water safety measures?

Awareness about the issues raised and the best choice (available technologies) fitting the strategic situation is significant in decision making. All kind of stake holders like policy makers, Government officials, engineers and consumers need to do capacity building and awareness.

Twin Pit Toilet is the commonest type adopted under various sanitation programs because it is the most convenient type among different options available.

Nowadays an inclination towards UDDT toilet is increasing. Surprisingly many of those concerned recommend UDDT as a panacea for all the problems which is not so. While I agree that UDDT toilet does have some merits, there are some issues with this type which limits its widespread extension. Some such issues are

i) It needs very high degree of users’ understanding & attention in terms of usage & maintenance.

ii) The methods of anal cleansing (use of water) also have a bearing on the successful operation of these toilets.

iii) Improper covering of excreta by every user with ash / saw dust etc is also a crucial point of failure of this type. There are many UDDT type toilets in the field which have failed for want of above expectations from users and have created an unhygienic atmosphere.

Much is needed to be done through R& D efforts about the design of toilets. In case of pit toilet it is essential to repeat the research with all the parameters on the background of the changed scenario (like large scale construction, different geo-hydrological situations etc). The other areas of research could be the study of happenings in the field with common types such as pit toilet, septic tanks & UDDT toilets, remedies / improvements in the present designs / practices. There should be efforts to evolve new types of toilets but keeping in mind the geophysical conditions, economics, water & energy issues, sociological issues etc

Christoph Platzer, CEO of KomveX, an m2m service company, Florianópolis, Brazil

I would like to respond to your first point – groundwater contamination. I see pit latrines very questionable in densely populated areas, especially with high groundwater levels used for drinking water purposes. And it is a severe threat, as there is no easy solution for this technology.

The only measure I see is a totally sealed pit, but in this case you would be creating almost an uncontrolled “anaerobic digester”, besides the problems of removal of the material. Rodent menace in leach pits is a severe threat to public health when you have shallow wells. There are two critical aspects: The fecal coliform contamination and Nitrate contamination. The problem with both is, that the water could be transparent and clean, containing both contaminations. People do not know about this and the direct threat has been proven very often.

The leaking of pit latrines in rainy season is also a severe problem for public health. I don´t see any measure one could have, if not putting it above ground and again sealing it totally. There have been quite a few studies about the “recommendable” density. There is no global number. The tolerable density depends on the type of soil, groundwater level, way of using the pit (no flush, hydraulic seal, cleansing water), number of users per toilet. In an urban setting where there is use of shallow wells, and the problem is very critical. An urban situation with centralized drinking water supply might support pits when there is 1.5m minimum distance to the ground water. When each house has a 200m² ground and there is no overflow situation (still there will be a nitrate contamination). I understand the cost aspect of Pit latrines but such a solution for me is no solution. So I think we have to look for an alternative. For me the alternative is UDDT (Urine Diversion Dry Toilet).

UDDT should be totally sealed, therefore no fecal coliform groundwater contamination and no influence of high water tables. As the process is dry, there is no danger of anaerobic processes (when well operated).There is a much lower contamination. I would infiltrate the urine due to cost reasons related to transport. With infiltration there is still a threat for the groundwater due to nitrate, but the possible densities without health threat are much higher.

Using a double vault, you come to a final product, which is much easier to be handled than the pit content. One does not have to change the locality. You don´t have smell therefore you can build it directly in the house. As it is sealed you don´t have any rodent menace and there are nice pans available for the same.

A step by step approach can be implemented towards a solution where a model for recollection of feces can be installed by a sanitation provider.

Disadvantages:

  • UDDT are more expensive than pit latrines, but people perceive it as a permanent and complete solution.
  • UDDT needs a slightly different user behavior. There is a need for social communication during introduction.
  • There are lots of badly executed UDDT examples. Therefore, good construction is crucial for a functioning UDDT.

Petra B, Student, United Kingdom

Community led Total Sanitation (CLTS) is an innovative methodology for mobilising communities to completely eliminate open defecation (OD). Unhygienic latrines can constitute fixed point open defecation. There is certainly awareness in CLTS practitioners about the danger of groundwater contamination through pit latrines. But this can be addressed at the triggering stage through good facilitation and community discussion of appropriate types of latrines.

Keziah Ngugi, Consultant in Water and Sanitation; Agriculture and food security, Kenya

Out of the seven billion people of the world, each produces 500lt of fecal matter per annum. If the pit was the toilet of choice for the whole world, imagine the billions of units we will be putting where we cannot retrieve for use. Even today, there are billions buried in this manner and more continue every day. Change from the burying to reuse is inevitable.

We need to campaign for the adoption of ecological sanitation and encourage recycling of the manure. It is one area where developing countries have failed miserably. Adoption of ecological sanitation will also address ground water safety issues, rodent menace in leach pits and hollowing of ground due to increasing density of pit toilets.

Hasani Makhubele, Manager: Sanitation Programme at National Department of Human Settlements, Nelspruit Area, South Africa

In South Africa, we are faced with a similar situation in rural and urban informal settlements. Due to scarcity of bulk water infrastructure and deteriorating sewer treatment schemes, it is difficult to avoid the provision of pit latrines to the poor and working middle class. In rural settlements, the spacial outlook is not dense compared to the urban informal settlements. However, ground water contamination remains a problem where appropriate technologies are not applied. The solution to the Indian situation could be the exploration of introducing technologies such as the enviroloos which are UDDT in nature requiring a high level of operation and maintenance.

Abdul Jamil, Independent Environmental Services Professional, Pakistan

Ground water contamination is really a major concern with higher ground water table. In such situations, it is a point of further consideration and research to go for dry pit latrine combined with separately diverting the urine to open/covered drains.

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