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Assessing demand for water supply and sanitation projects - optimising the selection of demand assessment techniques

Author(s): Parry-Jones, Sarah  |  Woodfield, Julie (ed)

Publisher: LSHTM | WEDC
Place of publication: London and Loughborough
Year: 1999

Series: WELL Studies in Water, Sanitation and Environmental Health Task 207
Collection(s): WELL


There is a well documented and recognised need to incorporate the expressed needs and demands of any target population to improve the sustainability of a project. Different sector professionals favour a variety of tools for use in a demand-responsive approach (DRA), and this study aims to explore issues and challenges surrounding the practice of demand assessment for water and sanitation services. It is based on the results of a detailed literature review, an electronic conference on DRA and a focused workshop. The target readership is DFID advisors, local project partners in government, NGOs and consultants involved in demand assessment and project identification.

The main research findings are:

'Demand' for improved water and sanitation is complex and is affected by a range of socio-economic and demographic factors, existing service provision and household attitudes towards government sector policy and the service provider. It is important to clarify what is meant by demand as different disciplinary professionals in the sector ascribe different meanings to it. This disparity works against an integrated approach.

Failure to understand the market for water supply and sanitation services results in wasted and unsustainable resources. However, rigorous application of a DRA ensures that supply can match predicted demand and that potential projects are realistic and achievable. Sometimes the constraints are such that there is only one option for action making a demand assessment study unnecessary. Demand for sanitation is more difficult to assess as it is measured in absolute terms rather than by degree, making it a supply-driven activity.

There are three main groups of assessment tools, used by different professional groups such as engineers, social scientists and economists: Household (HH) or Revealed Preference surveys (RPS), Participatory Rapid Appraisal (PRA) and Contingent Valuation Methodology (CVM).

The results of studies which have applied and tested these demand assessment approaches lead to the following broad generalisations:

The majority of cases in which CVM has been applied are from the World Bank series of studies;

Assessment of demand for water and sanitation services is often part of a single process in rural areas, using a range of techniques, but is more likely to be assessed separately in urban areas;

There is little literature on the use of participatory approaches to demand assessment in urban areas; and

Further work needs to be carried out on demand assessment for rural sanitation and the application of participatory approaches in urban and peri-urban areas.

General conclusions have been drawn about the applicability and validity of the different demand assessment techniques. HH and RPS methods are more relevant for providing information for city/district level decisions, than for small-scale rural surveys, when PRA is favoured as it facilitates a two-way communication flow. There is some debate about the appropriateness of CVM. Its opponents contend that there are alternative, simpler and cheaper participatory tools which are easier to transfer to developing country partners; its supporters promote it as the only technique to yield statistically representative data on anticipated responses to levels of service. There has been limited application of CVM to sanitation, where it does not appear to offer substantial advantages over other methods. The emphasis on CVM by the World Bank and DFID excludes other useful participatory methods and suggests that a more integrated approach is preferable which uses tools in parallel and optimises community involvement.

There is evidence of a general consensus on the importance of demand responsiveness, although there are more disparate views about how demand should be interpreted and assessed. Additional independent evaluation is required to inform understandings about the users? responses to consequent services and about how to promote a closer integration of tools and techniques.

Bibliographies  |  Contingent valuation  |  Demand Responsive Approach (DRA)  |  Participatory Rapid Appraisal  |  PRA  |  PROSPECT  |  Surveys  |  Zambia