This paper deals with the representation of continuous system dynamics into a timed discrete-event formalism to the end of system analysis. The continuous model of the system is first approximated using intervals and then translated into the timed automata formalism by comparison with thresholds defined on the state variables' domains. The detection of thresholds crossing is characterised by two time instants corresponding respectively to the earliest and latest crossing dates. This approach is briefly illustrated with real data obtained from a 1 m3 wastewater treatment pilot plant.