What is on-site sanitation? A case study of latrines

Updated - Monday 21 June 2004

Faq sheet on on-site sanitation latrines, prepared by CREPA, Burkina Faso

Introduction

There are different technologies available for dealing with waste water management and excreta. Some are suitable for dealing with off-site sanitation and others can be applied to on-site sanitation.

In this document the concept of on-site sanitation will be described, followed by the description of different types of latrines.

What is on-site sanitation?

1. What is sanitation?

Sanitation refers to excreta and waste water management as well as runoff water and solid and industrial waste. (6)

It is the whole range of strategies used to solve problems raised by excreta, solid and industrial waste and runoff water, excluding production and distribution of drinking water. (6)Two main types can be distinguished:

- off-site sanitation which is appropriate for large scale exploitation, based on technical and economic feasibility studies (sewer networks, runoff water drains, etc)

- and on-site sanitation.

2. The concept of on-site sanitation

a. Definition

On-site sanitation is the whole of actions related to the treatment and disposal of domestic waste water that cannot be carried away by an off-site sanitation system because of low density of population (technical guidelines on sanitation).

b. Characteristics of on-site sanitation

The autonomous part of on-site sanitation refers to the techniques used (purification of water), its design, as well as its financing, implementation and maintenance. (6)

Because the autonomous part of on-site sanitation is defined as such it is often regarded as the opposite of off-site sanitation, although the boundary between the two systems is not always as clear and well-identified.

In this context, we talk about:

  • individual on-site sanitation, when a house (plot) makes use of the soil as a treatment medium (example of soak-away, latrines, etc),
  • grouped on-site sanitation (or semi off-site sanitation), when many individual houses are linked to a network leading to a treatment system, or small communities: grouped sanitation doesn’t always use the soil as treatment medium (filtration beds, activated sludge are examples of purification systems at the end of the chain).

This classification is itself characterized by boundaries that are not clearly defined.

On-site sanitation latrines

1. Definition of a latrine

It is a site or a structure, located normally outside the house or building, destined to receive and store excreta and sometimes, to process it. The latrine is the most used sanitation system in the world. (6) Different types of appropriate latrines are used in on-site sanitation. This type of sanitation protects sensitive species of aquatic fauna by avoiding discharge concentrations in small waterways. Besides, it is cheaper than off-site sanitation, since the construction of a treatment plant is not required. When 1 gram of faecal matter can contain 10 million viruses, 1 million bacteria, 1 thousand cyst parasites and about a hundred worm eggs, it goes without saying, that a system that takes care of the storage and the disposal of excreta must be found.

2. Description of some types of latrines

Many types of latrines exist, some of which have been adapted and promoted by institutions such as CREPA. They can improve living conditions of populations and solve sanitation needs in developing countries. Conventional water born sewerage systems have been incapable of meeting populations’ needs in these countries. Sanitation technologies most commonly used nowadays are pit toilets and pour-flush toilets.(2)

a. Simple pit latrine or traditional latrine

It is a simple wooden or concrete slab installed over a pit of 2 m or more in depth. This support should stand on a sufficiently waterproof edge of the pit to avoid surface water (runoff and grey water) entering and destroying the facility. The pit should be lined in case of unstable soil where there is a risk of walls collapsing. However, in the case of lining, openings have to be provided in the walls to allow infiltration of liquid in the soil.

Excreta fall directly into the pit through a drop hole or a seat. This type of latrine is a simple pit covered by a slab with a drop hole. A superstructure is necessary to provide privacy and protection.

Advantages

  • Relatively cheap
  • Can be constructed by the user (particularly in rural areas)
  • Does not need water to function
  • Easy to maintain

Disadvantages

  • Considerable nuisance because of flies, insects (mosquitoes if pit is wet)
  • Bad smell

b. Ventilated improved pit latrines (VIP)

These are also called self-ventilated improved pit latrines. The principle is to cancel or to reduce harmful side-effects (smells and flies) related to traditional latrines by providing a vent pipe higher than the superstructure. This vent-pipe is fitted at the end by a mesh that stops flies from entering. Wind that blows at the top of the pipe creates an ascending air current between the pit and the outside atmosphere, and a descending air current between the superstructure and the pit through a drophole. Smells are evacuated through the vent pipe.

Advantages

  • Relatively cheap
  • Can be constructed by the user
  • Does not need water to function
  • Easy to maintain
  • No smell and no flies
  • It can take different sorts of cleansing materials (solid and liquid)
Disadvantages
  • Darkness is indispensable within the superstructure to fight off flies
  • Only functions properly when conveniently oriented towards the wind
  • No surrounding obstacle (trees and buildings) should be higher than the vent pipe

There are two types of VIP latrines: one pit latrines and double or multiple pit latrines.

c. Pour-flush latrines or toilets

A pour-flush latrine is composed of a pan with a water-seal installed in a superstructure. The water-seal is connected to a pit by a pipe. In certain cases, the water-seal can be installed on the slab of the latrine. The water-seal flushes out excreta with just enough water to drain off the solids and to restore the water level in the water-seal. Another advantage of the water-seal is that it stops flies and smells from coming out of the pit.. The pit can be dug far from the superstructure and connected with a pipe or covered drains. The pan is laid down on the floor on top of the water-seal for urine reception, under minimal hygienic conditions.

Advantages

  • Relatively cheap
  • No smells, no flies and mosquitoes
  • Agreeable to use
  • Can be improved by a connection to a sewer network at the right moment
  • Low water consumption 2 – 3 litres of water for each flush

Disadvantages

  • A source of water is needed
  • The use of solid cleansing material is not advisable (except paper)
  • Skilled labour (mason) is required

There are two kinds of VIP latrines: pour-flush latrines with one pit and pour-flush latrines with double or multiple pits

d. ECOSAN latrines (ecological sanitation)(7)

Ecosan latrines are latrines that ensure the recovery of waste by separating urine and faeces in view of their reuse in the fertilization of soil for agricultural purposes. (reintroducing nutrients into the soil such as: nitrogen, phosphorous and potassium).

The variety of available eco-sanitation systems helps, in most cases, to choose a system that is culturally acceptable. The issue of cost is relative, some systems are complicated and expensive, others are simple and cheap. There is always a compromise to be made between cost and functionality: cheap solutions imply more handling and maintenance of sanitation systems. In the case of more expensive systems, there could be less handling and maintenance. These latrines have been set up in order to preserve the environment and to recover waste products. Pits are completely lined and the bottom is waterproof in order to avoid infiltration into the soil.

An eco-latrine is composed of a pit constructed above ground. The pit is covered by a slab on which a superstructure is built. The pit is ventilated like the VIP latrines but its volume is less important, because the filling time calculated is less than a year. The storage of ash inside the superstructure (in a bowl) is advisable so that it can be mixed with the excreta, after every use, in order to control the moisture content. A tank installed outside the superstructure is used for the storage of the urine.

Advantages

  • Recovery of urine and waste products
  • No pollution of ground water
  • Very hygienic
  • Easy to maintain
  • Does not need water to function

Disadvantages

  • Containers for urine storage are needed
  • Water is not recommended for cleansing
  • Addition of ash is required after every use
  • Overhead pits require climbing stairs to access the facility
  • Skilled labour (mason) is required

Apart from these latrines described above, there are other facilities which also have advantages and disadvantages. They are: cat latrines, composting latrines, septic tank latrines, aqua privies, etc.

For more information, look at the following web site (5): http://www.oieau.fr/ReFEA/module3b.html

It is important to know that the choice of the right latrine is based on a series of studies that go into all the relevant factors which need to be considered for an efficiently functioning latrine. CREPA can be of assistance in this process.

References

[1] Wagner, E.G.; Lanoir, J.N. Evacuation des excréta dans les zones rurales et les petites agglomérations - (Disposal of excreta in rural and small scale agglomerations) - Geneva (CH): OMS, 1960.- 196 p. - 46 ref. - Series : OMS, Série de monographies, N° 39

The actual study which deals with the disposal of excreta in rural areas and in small agglomerations highlights the different types of latrines, the draining systems and the excreta disposal programmes in rural areas. In the appendix of the study, the training of professional and technical public health service staff is mentioned as well as a list of experts who have examined the preliminary text. The basic objective of this study is to promote the installation of excreta disposal facilities in rural households.

[2] Franceys, R.; Pickford, J.; Reed, R. Guide de l ' assainissement individuel - (Individual sanitation guidelines) - Geneva (CH): OMS, 1995.- 258 p. - ref. - ISBN : 92-4-25443-4

This document deals in depth with the design, the construction techniques, the exploitation and maintenance of the main types of individual sanitation facilities. Concrete examples are mentioned, from the simple pit latrine to the septic tank. The setting-up of individual sanitation systems involves more than the simple implementation of a certain number of techniques. The authors describe in detail the process of planning and development, as well as the financial and institutional aspects, which have to be taken into consideration. They emphasize, especially, the necessity to involve the local community in all stages of the project, from the planning right to the evaluation stage and to adapt projects and programmes to local conditions, continuing the support to a community, once the facility is in place.

[3] CREPA//Centre Régional pour l’Eau Potable et L'Assainissement à faible coût /Ouagadougou/BF - (Regional low cost water supply and sanitation centre). Fiches techniques des ouvrages d ' approvisionnement en eau potable et d ' assainissement (AEPA) - (Specification sheets on water supply and sanitation facilities.)- Ouagadougou (BF): CREPA, 1996.- 84 p. - ill., tabl. - Series : Document technique, N° 2

It is CREPA’s ambition is to create and promote appropriate water and sanitation technologies adapted to socio-economic and cultural conditions of the country members in the water group. It has successfully realised facilities like ventilated improved pit latrines, rain water catchment tanks, hand washing facilities, and many others throughout Burkina Faso. This technical book is a compilation of specification sheets of facilities, which gives detailed information on those projects that work well.

[4] CREPA/Centre Régional pour l’Eau Potable et L'Assainissement à faible coût /Ouagadougou /BF - (Regional low cost water supply and sanitation centre). Manuel sur la construction, l ' entretien et l ' exploitation des toilettes à chasse manuelle (TCM) type dagnoin - (Construction, maintenance and operation manual on pour-flush latrines.) - Ouagadougou (BF): CREPA, 1994.- 33 p. - ill.

This construction and maintenance manual on potable water storage facilities (PEP) is in keeping with a joint CREPA-WHO programme oriented towards hygiene promotion in low income communities. All the relevant steps to get the facilities up and running are listed in this manual.

[5] Assainissement : latrines - (Sanitation : latrines)OIEau/CREPA, web site.:http://www.oieau.fr/ReFEA/module3b.html

This web site provides information on: general presentation, conception, construction, design of the pit, exploitation, etc of latrines. You will find sections on; questions and answers, knowledge tests, references and other low cost technologies.

[6] Chocat, B. Encyclopédie de l ' hydrologie urbaine et de l ' assainissement - (Urban hydrology and sanitation encyclopaedia.) - Paris (FR): Lavoisier Tec et Doc, 1997.- 112 p. - ill., tabl., graph. - ISBN : 2-7430-0126-7

This document contains many specific terms related to urban hydrology and sanitation, from sanitation systems to treatment plants and rain water drainage methods.

[7] Esrey, S.A.; Gough, J.; Rapaport, D. Assainissement écologique – ( Ecological sanitation) - Stockholm (SE): SIDA, 1998.- 92 p. - ill. - ISBN : 9158676120

This document talks about sanitation in relation to ecology. On-site sanitation is an important subject in this document and human waste (excreta and urine) has been analyzed and tested for its risk free use in an ecological environment, under the provision that the technologies are managed correctly.

Contact persons

  • Cheick Tidiane TANDIA, General Director of CREPA, 03 BP 7112 Ouagadougou, Burkina Faso 03 Tél.: 00 226 36 62 10 or 36 62 11 Fax : 00 226 36 62 08
  • Karim SAWADOGO, Technical officer at CREPA, 03 BP 7112 Ouagadougou 03 Tel.: 00 226 36 62 10 or 36 62 11 Fax : 00 226 36 62 08

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Date written: 09 Jan 2004

Date revised: 7 Jun 2004

Author: Cheick Tidiane TANDIA, General Director

Organisation: Centre Régional pour l'Eau Potable et l'Assainissement à faible coût (CREPA), Burkina Faso

Reviewed by: Trea Christoffers, Programme Officer, IRC

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