Three studies on cost-effectiveness and cost-benefit analysis have been published in the latest issue of the Journal of Water and Health (each article costs £ 20). The first two are based on earlier work (available for free) published by WHO.
Haller, L. ; Hutton, G. and Bartram, J. (2007). Estimating the costs and health benefits of water and sanitation improvements at global level. Journal of water and health ; vol. 5, no. 4 ; p. 467–480. doi:10.2166/wh.2007.008
Hutton, G. ; Haller, L. and Bartram, J. (2007). Global cost-benefit analysis of water supply and sanitation interventions. Journal of water and health ; vol. 5, no. 4 ; p. 481–502. doi:10.2166/wh.2007.009
Clasen, T.; Cairncross, S., Haller, L. ; Bartram, J. and Walker, D. (2007). Cost-effectiveness of water quality interventions for preventing diarrhoeal disease in developing countries. Journal of water and health ; vol. 5, no. 4 ; p. 599–608. doi:10.2166/wh.2007.010
From the abstract: Using effectiveness data from a recent systematic review and cost data from programme implementers and World Health Organization (WHO) databases, we conducted a cost-effectiveness analysis to compare non-piped in source- (dug well, borehole and communal stand post) and four types of household- (chlorination, filtration, solar disinfection, flocculation/disinfection) based interventions to improve the microbial quality of water for preventing diarrhoeal disease.