Frank Rijsberman's paper on the challenge of water and sanitation provision attracts considerable agreement from the authors of the two opponent papers. John Boland, in particular, is sympathetic to most of the analysis, although he has some doubts about the ease of implementation of the proposals. Henry Vaux, although accepting many of the arguments put forward, has one point of substantial disagreement: He believes that the water challenge is largely defined by scarcity, whereas Rijsberman takes the view that is primarily an issue of fair and effective access.

Vaux agrees with the challenge definition as provision of water and sanitation to the unserved. However, he considers the Millennium Development Goal as an unrealistic basis for quantitative analysis. To halve the numbers of unserved by 2015 implies, for example, bringing sanitation to 825,000 unserved people each day from now until 2015. In his words, this does not seem “physically, institutionally, or economically attainable.” By extension, the benefits of the proposals would be lower.

He emphasizes the critical point that interventions must be made in combination, and should link appropriate technology with effective institutions. The neglect of institutional problems has in the past led to the failure of many schemes. He also concurs with the point that water and sanitation are necessary but not sufficient for economic growth to occur.