Bangladesh has the largest proportion of people exposed to arsenic contamination in water. Studies have shown that awareness campaigns have positively influenced communities regarding their choice of safe water sources. In order to reach and engage communities in adopting safe water supply systems, there is scope in using smartphones to help in monitoring, operation and maintenance and bringing awareness around water safety. The Tapp-BDP app is being developed to tackle this. Its desired functionalities are: water quality field testing, service delivery, payment, interaction, and a knowledge domain on water safety. Specific to the knowledge domain of the app, the challenge is to digitally convey a complex topic in an understandable manner to improve trust within the water supply system and to empower the stakeholders to take charge of their own water supply. ICT provides the opportunity to quickly convey knowledge in new, attractive ways, but is not always inclusive to all. Through the investigation of the complex water safety context, the attributes of the target group as well as using smartphones as a communication channel the outcomes of this project resulted in a set of guidelines that support the development of digital knowledge.@en