This paper analyses the tension field between digitalisation, sustainability and knowledge management in the water sector, particularly, in the context of climate change and water stress. The importance of sustainable hybrid drinking water supply and simultaneous flood protection is outlined by a practical case study within a German water association with a total volume of around 100 Mio. EUR. An ongoing evolutionary digitalisation project is presented and research propositions are stated, which are centred on the questions of deployment of sustainable critical success factors (CSFs) based AI-solutions paired with knowledge management systems (KMS) in the context of climate change and water stress. The application of CSFs and the creation of digital and rational decision-making models based on KMS are elaborated on. Additionally, it is elucidated, whether digitalisation, knowledge and sustainability are to be seen as CSFs in themselves, which thereinafter is confirmed. Finally, the possibility of integrating Kingdon’s multiple stream model into an AI-based KMS to provide management decision support is explained. In conclusion, knowledge is seen as a binding key for achieving a sustainable digitalisation strategy within a critical infrastructure organisation.