is timely. Inter-disciplinarity is always difficult. In the water sector such difficulties have been magnified not just by the perversity of its tribal dynamics but especially because the political stakes are high. This account and response will not meet the standards of philosophical analysis set by Merrett. It is written in the spirit of having a further impact on an important on-going discourse. And in the hope that the ideas reach water policymakers. Others might want to comment on whether they think virtual water is a scientifically respectable term or perhaps that it is just a potentially misleading, though useful, metaphor.