Community-based flood early warning systems (CBFEWS) are effective at reducing flood risks for vulnerable communities, but they are generally initiated, funded, and managed by external agencies. They need to be localised, preferably with the involvement of local government bodies, and made sustainable. The sustainability of a CBFEWS beyond the termination of funding assistance needs the sustenance of at least four elements: financial, institutional, technological, and social. To increase sustainability, stakeholders must take ownership of the system and develop a standard operating procedure.