This would emphasise the need to value benefits or disbenefits at all steps of the value chain and to evaluate whether current levels of investment for each of these steps is adequate. Based on the study findings, it appears that conducting a global study of the benefits of investing in WSS, such as the Stern Review for climate change or the Millennium Impact Assessment for ecosystem services, would both be extremely challenging and of comparatively more limited use. From a practical point of view, the present report has repeatedly highlighted the variability in benefits from WSS depending on local factors, such as the prevalence of diarrheal diseases, the quality of receiving waters, etc.