The purpose of this contribution is first, to respond to the request for clarification of the term 'virtual water' by Stephen Merrett. Second, it provides a narrative for those who might not be aware of the origin and development of the concept. Third, the discussion will draw attention to the problems encountered in gaining entry for the idea into those water policy discourses where the it was most relevant. The concept has been in currency for almost a decade. The use of the term increased rapidly after 1995 and by the millennium the idea had become central to many dialogues relating to water security preliminary to the Kyoto World Water Forum in March 2003. Merrett's (2003) challenge that the water community should give attention to the language used by its diverse professionals and scientists is timely. Interdisciplinarity 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. (Tony Allen)