The present work is directed to the analysis, design and construction of web-based systems capable of catalysing processes of stakeholder participation in such ways as to realise changes that are judged by these stakeholders as positive in the water sectors of both the human and the natural economies. The thesis is advanced that the judgement that is so passed is a recognition on the part of the stakeholders of a realisation of social justice. This paper is thus given over in its first part to an analysis of the origins and the nature of social justice in this sector. It is emphasised that, although the resources of hydroinformatics in this endeavour are largely based upon quantitative assessments, the ways in which these translate through stakeholder participation into experiences of social justice are essentially qualitative. Thus, although we are currently concerned for the most part with a hydroinformatics of the quantities, this now has to be extended into a hydroinformatics of the qualities.