"Science-based" standards are an integral part of modern regulatory systems. Studies on "public understanding of science" mostly focus on high technology areas in advanced economies. In contrast, the present study analyses the public understanding of regulation in the context of standard-setting for bottled water quality in India. Using primary data, the econometric models of this paper show that public understanding of participation in regulation depends on awareness of, and trust in, existing regulatory practices in a complex, non-linear manner. In this light, the paper argues that "deficit model" and "dialogue model" frameworks cannot be seen as two mutually exclusive frameworks of analyses.