A realistic and scientific risks communication system is inevitable for better risk awareness and improved disaster preparedness. Conventional disaster management studies paid much attention on the contents of the information, and ignored the importance of information source. Since natural disasters are uncertain and complex, individuals decisions on disaster issues depend much on their trust in risk information source. This study systematically examines the role of trust in risk awareness and preparedness. The study is based on field surveys conducted in two flood affected slum communities in Mumbai, India. The study has revealed that higher trust leads to higher risk awareness and better acceptance of perusing preventive action. To take decision on impending risk or early warning, individuals depend most on the local city authority because the community believes the city authority is having better flood management skill and knowledge. The degree of acceptance of flood preventive measure depends on how much risk communicating agency cares and concerns about community's interest. In this study, responded reported mass media is the one who cares most about community's interest. The role of local leaders is negligible in entire risk communication process, because the local community does not have much trust in local leaders. The study reestablished that trust in risk communication sources is inevitable for improved disaster risks communication.