Municipal infrastructure in Norway is built primarily by small specialist companies acting as subcontractors, mostly with minimal experience working with Information and Communication Technology (ICT). This combination of inexperience and lack of resources presents a unique challenge. This paper applies Model-Based Systems Engineering (MBSE) using the Systems Modelling Language (SysML) to combine validation of reliability and security requirements within a mission-aware interdisciplinary context. The use case is a 6LoWPAN/CoAP-based system for urban spill water management.