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Comparing Willingness to Pay for Improved Drinking-Water Quality Using Stated Preference Methods in Rural and Urban Kenya

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Abstract

Background

Access to safe drinking water has been on the global agenda for decades. The key to safe drinking water is found in household water treatment and safe storage systems.

Objective

In this study, we assessed rural and urban household demand for a new gravity-driven membrane (GDM) drinking-water filter.

Methods

A choice experiment (CE) was used to assess the value attached to the characteristics of a new GDM filter before marketing in urban and rural Kenya. The CE was followed by a contingent valuation (CV) question. Differences in willingness to pay (WTP) for the same filter design were tested between methods, as well as urban and rural samples.

Results

The CV follow-up approach produces more conservative and statistically more efficient WTP values than the CE, with only limited indications of anchoring. The effect of the new filter technology on children with diarrhea is among the most important drivers behind choice behavior and WTP in both areas. The urban sample is willing to pay more in absolute terms than the rural sample irrespective of the valuation method. Rural households are more price sensitive, and willing to pay more in relative terms compared with disposable household income.

Conclusion

A differentiated marketing strategy across rural and urban areas is expected to increase uptake and diffusion of the new filter technology.

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Notes

  1. The average exchange rate (Ksh to US$) in the month of January 2012 was 0.0114.

  2. The outcome of the likelihood ratio (LR) test when comparing the preference parameters between the two models for Nessuit and Nakuru, whilst keeping the scale parameter constant, was 27.4 (p < 0.002). The equality of scale parameters is rejected at p < 0.01 by the same test (LR = 11.39, 1 degree of freedom).

  3. Attribute attendance was also tested by estimating latent class models for both subsamples using the so-called 2K model in NLOGIT 5, and we found that a larger share of the respondents in the rural sample did not consider storage capacity in their choices. The attribute flow rate was ignored in both samples, as is reflected in its statistical insignificance.

  4. This was the only variable that also produced a significant interaction effect with the diarrhea choice attribute in the urban sample.

  5. The standardized Mann–Whitney test statistic comparing the two contingent valuation willingness-to-pay values equals −11.723 (p < 0.0001).

  6. Test results are available from the authors upon request.

  7. The Mann–Whitney test statistic comparing the central tendency of the relative share of willingness to pay with household income between the two samples equals −7.475 (p < 0.0001).

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Acknowledgments

Financial support provided by the Netherlands Organisation for International Cooperation in Higher Education (Nuffic) for Fumbi Crescent’s stay at Eawag is gratefully acknowledged. Roy Brouwer carried out this work as part of his appointment at Eawag.

Conflict of interest

Roy Brouwer, Fumbi Crescent Job, Bianca van der Kroon, and Richard Johnston confirm that no conflicts of interest exist in relation to the publication of this article.

Contributions of the Individual Authors

Roy Brouwer contributed to the design of the questionnaire, design of the CE, and analysis of the collected data, and is the main author of the paper. Fumbi Crescent Job helped with the design of the questionnaire and was responsible for the data collection. He carried out the pre-tests together with Bianca van der Kroon, and entered the data in a database. Bianca van der Kroon helped with the design of the CE, pretesting of the questionnaire, and contributed to the analysis of the data and helped with the writing of the paper. Richard Johnston helped with the design of the questionnaire.

Author information

Authors and Affiliations

  1. Department of Environmental Economics, Institute for Environmental Studies, Vrije Universiteit, De Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands

    Roy Brouwer & Bianca van der Kroon

  2. Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland

    Fumbi Crescent Job

  3. World Health Organization (WHO), Geneva, Switzerland

    Richard Johnston

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  1. Roy Brouwer
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  2. Fumbi Crescent Job
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  4. Richard Johnston
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Corresponding author

Correspondence to Roy Brouwer.

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Annex

Annex

See Table 6.

Table 6 Estimated choice models for GDM disinfection water filters in the urban and rural samples including choice attributes only
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Brouwer, R., Job, F.C., van der Kroon, B. et al. Comparing Willingness to Pay for Improved Drinking-Water Quality Using Stated Preference Methods in Rural and Urban Kenya. Appl Health Econ Health Policy 13, 81–94 (2015). https://doi.org/10.1007/s40258-014-0137-2

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