Rainwater harvesting technology is considered an innovative and effective mechanism for reducing drinking water risks due to arsenic contamination and water salinity in coastal Bangladesh. However, adoption of such tanks remains elusive. Most studies on disaster risk communication are predominantly based on individual-level cognitive modeling approaches, which fail to address the role of social groups, human relations, and other collective social factors in the dissemination process of disaster preventive measures. From the viewpoint of social implementation, community adoption of unfamiliar technology for disaster risk mitigation and preparedness requires another approach. Given the challenge to promote rainwater harvesting technology in the study area of coastal Bangladesh, this study examines the role of various social networks including cohesive groups (friends), structural equivalent groups (individuals who have the same position in society), and spatial groups (neighbors) in three information sharing and processing activities—hearing, observation, and discussion. Results show that those individuals who have similar cohesive affiliations tend to become hearing and discussion partners. Cohesive groups share a learning opportunity and are bounded by normative constraints in terms of direct and intimate social relations. Spatial groups facilitate observation, which provides visual learning. Structurally equivalent groups are not relevant in adoption dissemination; therefore competition or similar social environment did not influence the rainwater tank dissemination activities.

Participatory flood risk mapping (PFRM) is a well-recognized and widely implemented tool for meaningful community involvement in disaster risk reduction (DRR). The effectiveness of PFRM remains anecdotal. The PFRM exercise has rarely been applied identically in two different places by two different organizations, which produces varied and uncertain outcomes. In the absence of any agreed and comprehensive framework for participatory DRR, existing studies struggle to provide a scientific account of how the structure, design, and process of PFRM ensure the effective participation of local communities. This study, examines what factors and methods make PFRM an effective participatory DRR tool. In this study, we first identified the process-based criteria of participation. Then we briefly introduced a participatory flood risk mapping exercise conducted in a flood-prone informal settlement in Dharavi, Mumbai. The exercise was carefully designed to meet the process criteria of effective participation. Finally, using qualitative research methods, we evaluated the effectiveness of our PFRM from the local community perspective. The findings show that ensuring community livelihood security and true involvement of marginalized groups, preparing an action plan, and incorporating fun and cultural connotations into the facilitation process are critical components that enhance community participation through PFRM in DRR.