Page d'accueil   |  A propos de cette collection  |  Aide  |  Effacer       Anglais  |  Français  |  Espagnol  
Document complet
Dérouler chapitre
Etendre sommaire
vers la section précédente vers la section suivante

fermer ce livreA Guide to the Development of on-site Sanitation (WHO; 1992; 246 pages)
Afficher le documentPreface
ouvrir ce répertoire et afficher son contenuPart I. Foundations of sanitary practice
ouvrir ce répertoire et afficher son contenuPart II. Detailed design, construction, operation and maintenance
fermer ce répertoirePart III. Planning and development of on-site sanitation projects
fermer ce répertoireChapter 9. Planning
Afficher le documentThe demand for sanitation
Afficher le documentProject definition
Afficher le documentBackground information
Afficher le documentComparison and selection of systems
ouvrir ce répertoire et afficher son contenuChapter 10. Institutional, economic and financial factors
ouvrir ce répertoire et afficher son contenuChapter 11. Development
Afficher le documentReferences
Afficher le documentSelected further reading
Afficher le documentGlossary of terms used in this book
Afficher le documentAnnex 1. Reuse of excreta
Afficher le documentAnnex 2. Sullage
Afficher le documentAnnex 3. Reviewers
Afficher le documentSelected WHO publications of related interest
Afficher le documentBack Cover

Background information

Careful consideration should be given to all relevant factors in order to decide on the most appropriate form of sanitation and the most effective way of providing it. These factors include public health, socio-economic, cultural, financial, technological, institutional, and other considerations.

A large unified project may require several reports by agency officers or consultants. Long written reports are unnecessary for small projects and for programmes that consist of a succession of small schemes. However, whether a large or small scheme is planned, all relevant factors need to be carefully considered.

The responsible agency

The planning and implementation of a simple programme for a few households may be within the capacity of a small committee of interested people, preferably with an enthusiastic leader. Larger programmes may depend on government initiative, or on the support of an external body such as a bilateral agency, one of the international organizations, or a local nongovernmental organization. The degree of involvement of an agency varies considerably according to the nature of the project, the type of agency and other national and local conditions.


Staff employed to plan sanitation projects should be carefully selected and prepared. Unless they have previously worked on similar programmes, the people appointed should receive formal or informal training, preferably on site with an existing sanitation project. It cannot be too strongly emphasized that the staff involved in all stages of a low-cost sanitation programme should be familiar with technological, management and sociological issues. They should also be familiar with the local financial and socioeconomic conditions, i.e., the standard of living of the local communities, and be aware of the important role that women, social workers and nongovernmental organizations can play.

Community participation

The involvement of the community in any project is essential for its success, because almost all on-site sanitation work depends on decisions made by individual householders. The extent of involvement will vary in different countries. Urban communities often play a role that is quite different from that undertaken by village people, and this is likely to be different again from that of those living in dispersed family units. Some groups of people are homogeneous; others comprise various cultures and socioeconomic levels.

Key leaders

Early contact should be made with key leaders, who may sometimes be identified with the assistance of the local health officials. The key leaders may be the chiefs and elders of villages, or people appointed by the government or political party. In some areas local schoolteachers or business people with education above the average may be useful as sources of local information and for an exchange of views.

Minority groups

Whoever are selected as key leaders, care must be taken to ensure that the views of all sections of the community are represented. It may be necessary to seek out leaders of minority groups and representatives of those without political influence. In particular, the views and support of women should be sought. These are often best obtained by women social workers.

Community needs and aspirations

Initial assumptions regarding the need for improved sanitation in the area as a whole and particularly in priority areas should be verified through contacts with key leaders and health workers. In particular, the incidence of excreta-related disease should be checked, as should awareness of relationships between sanitation and disease and of other disadvantages of existing excreta disposal practices, such as fly nuisance.

Care must be taken to avoid raising unreasonable expectations. At the same time, the local people should be made aware of the potential benefits of improved sanitation. When possible, even at the initial survey stage, key leaders should visit nearby completed projects to see good latrines in use. Simple drawings and models may also be used so that alternative technologies can be discussed.

Some idea of the readiness of the community to provide labour, money and materials for a latrine-construction programme should be obtained. Considerable skill is required to find out the true aspirations and priorities of the people. Answers to questions are often distorted because the interviewees wish to please the questioners. Small group discussions with minimum intervention by outsiders may be an effective means of finding out the true local opinion.

Survey of the area

The most appropriate sanitation is that which best meets the needs and aspirations of the people within all local constraints. In order to assess what is most appropriate, a survey of the district should be carried out.

The survey may include both secondary and primary data. Secondary data are obtained from existing reports, maps and statistics. These should be critically examined and due allowance made for possible inaccuracy. For example, the information may not be up to date, or it may have been obtained from unreliable sources or collected hurriedly. Study of the available secondary data will reveal gaps that need to be filled by primary data.

Primary data are obtained by direct and indirect observation, measurement, household surveys, interviews and informal conversations. Care should be taken to ensure that those carrying out the survey have been properly trained. Any questionnaires used should be carefully planned to ensure that the answers reflect the true opinions of respondents.

A survey for a sanitation project may include the items listed below. In addition to information about the existing situation, any proposals for changes (and when they are likely to occur) should be noted.

Physical factors

Of greatest importance is the local geology - the underlying rocks and the nature of the soil, in particular, how easy it is to dig and how stable the soil remains after excavation. It is also important to determine whether the soil is permeable so that water drains away, the depth of the top soil, how the soil varies with depth, the depth of hard rocks in which it is difficult to dig, and whether there are any fissures or boulders.

Natural gradients and the natural surface water drainage system should be noted, especially if there is much local variation. This may involve a study of the surface water hydrology and the climate, particularly the seasonal rainfall pattern. Areas that are subject to regular or occasional flooding should be noted. Any information that can be obtained about groundwater may also be useful, for example, the depth of the groundwater table, whether there is any seasonal variation or long-term change, the directions in which the groundwater flows, and its quality.

Existing excreta disposal methods

It is essential to obtain as much information as possible about existing sanitation. A programme is usually intended to rectify an unsatisfactory situation and the extent of deficiency in sanitary provision is the baseline from which it starts. Any existing local sanitation that is satisfactory could give an indication of the most appropriate general solution. Improvements to existing systems are likely to be more acceptable than completely new ideas. In addition, examination of existing sanitation may provide useful technical information regarding such matters as soil infiltration capacity and rates of accumulation of solids.

Another advantage of obtaining accurate and complete information about existing sanitation is that it can contribute to the evaluation of the completed programme.

Water supply

The service most closely related to sanitation is water supply, and careful note should be made of all water sources in the community. If possible, water sources should be visited and inspected. Claims by water authorities regarding the piped water supply service are often exaggerated, and the existence of water pipes and fittings should not be taken as evidence of satisfactory delivery of water. Pressure at the end of a long pipeline is often low, and the supply may be intermittent. Many people find it difficult to estimate distances in rural areas, so whenever possible the journey to collect water should be observed and timed.

Special care should be taken to check information relating to dependence on groundwater as a source of drinking-water. The depth of the water table and the location of wells and boreholes are particularly important because of the risk of pollution from pit latrines and soakpits. If possible, an analysis of the groundwater, including bacterial contamination and nitrate concentration, should be obtained. Comparison with analyses after the sanitation project has been implemented can then be used to monitor any groundwater pollution.

Health and disease

The need for improved sanitation may be gauged from information about the prevalence of excreta-related diseases. Sometimes attendance records at local health centres yield this information, particularly in relation to diarrhoeal and parasitic diseases. However, the value of records depends upon the accuracy of diagnosis, the care with which records are kept, and the location of the health centre relative to the area served.

Data obtained in a health survey carried out before the start of a project may be compared with data from another survey after the project has been implemented as a means of assessing the effectiveness of improvements in sanitation. However, such baseline surveys are expensive and difficult to carry out successfully. They are normally only required where governments or donors require evidence of the efficacy of simple sanitation.

Population and dwellings

Information obtained previously about the number of people and the number of houses to be served by the project should be checked and supplemented as necessary. Detailed demographic data, such as age and sex distribution may be significant, especially if it is customary for workers to move away from the area temporarily or permanently. Trends in any migration patterns should also be noted.

Aspects of housing that most affect sanitation are density, quality and level of occupancy. While low densities overall are usual in rural areas, it is not uncommon for dwellings in villages, and even in isolated family compounds, to be clustered at high density. The most relevant statistics are the open space belonging to each dwelling and the number of people occupying each dwelling. The quality of housing may indicate the economic level of the people and the efforts they are likely to put into improvements, including the construction of latrines. In many rural and periurban areas the majority of dwellings have been built by the occupants, who are therefore responsible for their own sanitation facilities. Improving the sanitation may be complicated where the occupant is not the owner, where a single dwelling is shared by several families, or where people occupy the upper storeys of multistorey buildings.

Culture and traditions

Customs that influence the selection of the most appropriate type of latrine include:


• the preferred method of anal cleaning (water or solid material such as paper, leaves, stones, grass or corncobs);

• whether it is customary to defecate squatting or sitting;

• the degree of privacy favoured;

• the preferred location of latrines in relation to dwellings;

• any preference for bathing in the latrine after defecating;

• traditional use of human excreta or compost derived from human excreta as a fertilizer;

• objections to handling excreta, even when they have completely decomposed;

• any restriction regarding the use of the same defecation place by different groups, for example a taboo on use of the same place by men and women, adults and children, or even more specific categories such as fathers-in-law and daughters-in-law;

• any objections to the use of communal or family defecation places by certain people at certain times, such as women while menstruating.

Communication and education

The ability and willingness of communities to accept new ideas, including new ideas about excreta disposal, are likely to be influenced by the extent of their outside contacts. In many places there is regular exchange of information through meeting people from other areas at markets, or when attending social functions. Literacy levels may determine the extent to which written or printed advice or instructions can be understood. It may be useful to find out how many members of the community own radios and television sets and whether they are in working order, and how many people read newspapers or see film shows, and in which languages. Understanding local terminology and traditional modes of communication, such as drama and song, may also be useful.


While full information about employment of the local people is useful as background, of particular importance to sanitation planning is the location of workplaces. The practice of spending a high proportion of each day on farms that are distant from dwellings may influence the design of household sanitation. Similarly the extent of other activities away from home, such as attendance at markets or industrial employment, may point to a need to provide latrines at these places. Any seasonal variation in economic activity, income level, and location of workplace should be noted.

The environment

Cleanliness of private dwellings and yards, and also of public roads, footpaths and open spaces, may give a good indication of the likely interest of communities in improving excreta disposal facilities. Methods commonly used for disposal of solid waste should be noted.


Ease of access by vehicles should also be checked, bearing in mind that many rural roads that are reasonably good in dry weather may be impassable for several weeks or months during the rainy season. Vehicular access to properties may affect the choice of type of latrine, for example, where full pits need to be emptied by vacuum tanker.


While some householders may be able to build their own simple latrines, in many places construction will be undertaken by contractors or self-employed artisans. An assessment of the ability and reliability of local contractors and artisans is therefore required. The financial status of contractors may be relevant. Apart from latrine construction, firms or individuals may be able to prefabricate components, such as slabs, blocks, pans and pipes.

The availability and market price of materials and components likely to be used in the construction of latrines should be ascertained as accurately as possible. For material that can be obtained locally, such as sand and gravel, the actual cost of extraction and transport may be more relevant than market prices. Wage rates for skilled and unskilled labour should be noted.

Availability of internal finance

An assessment should be made of the likely contribution that beneficiaries will make to the cost of latrine construction and maintenance. Money available in rural communities usually depends on the sale of agricultural produce and its seasonal variation; cash may only be available at harvest-time. In any community there may be income from wages and salaries, and from remittances received from absent members of families.

Attempts should be made to estimate willingness to spend money on sanitation, although it must be realized that statements made by individuals or community leaders regarding ability or willingness to pay are often unreliable. Responders usually answer questions in a way they think will give them greatest benefit. They may think that if they claim to be poorer than they are they will receive more outside help, Alternatively, they may exaggerate their ability to pay if they expect that this will ensure the implementation of outside-funded improvements.

Ability to pay may be based on the income of poorer sections of the community. In some places it has been found that payments for improved sanitation by the poorest people should not exceed 1% of their income, but up to 3% is acceptable for other economic groups (Kalbermatten et al., 1982).

Availability of external finance

The fullest possible information should be obtained regarding grants, loans and subsidies likely to be available from local and central governments, bilateral donors, international and commercial banks, and other external sources.

vers la section précédente vers la section suivante

S'il vous plaît envoyez vos commentaires   Anglais  |  Français  |  Espagnol