A transient pressure event detection system for a pipeline network comprising: a data repository encoding route data on the pipeline network; a data receiver configured to receive pipeline sensor data from each of a plurality of sensors that are spaced apart in the pipeline network, the pipeline sensor data from each sensor being timestamped; an event detecting unit including a processor and a non-transitory memory and being configured to execute computer program code to: i) receive the pipeline sensor data from the data receiver; ii) determine, from the sensor data received from each of at least two of the sensors, in respect of each of the at least two sensors, a transient pressure event occurrence and the timestamp for the event occurrence's arrival time; the system being characterised in that it is configured to further execute computer program code to: iii) for all pairings of the sensors having a transient pressure event occurrence, determine, from the data repository, routes in the pipeline network between the sensors of the sensor pairing; iv) determine, for each route and in dependence on difference in timestamps of the respective sensors, a potential source location in the pipeline network for the transient pressure event; v) perform a simulated transient event for each potential source location and determine a modelled arrival time of a transient corresponding to the event at each of the at least two sensors; vi) compare the timestamp of the event occurrence for each of the at least two sensors with the modelled arrival time and selecting the potential source location corresponding to the closest modelled arrival time. a data repository encoding route data on the pipeline network; a data receiver configured to receive pipeline sensor data from each of a plurality of sensors that are spaced apart in the pipeline network, the pipeline sensor data from each sensor being timestamped; an event detecting unit including a processor and a non-transitory memory and being configured to execute computer program code to: i) receive the pipeline sensor data from the data receiver; ii) determine, from the sensor data received from each of at least two of the sensors, in respect of each of the at least two sensors, a transient pressure event occurrence and the timestamp for the event occurrence's arrival time; i) receive the pipeline sensor data from the data receiver; ii) determine, from the sensor data received from each of at least two of the sensors, in respect of each of the at least two sensors, a transient pressure event occurrence and the timestamp for the event occurrence's arrival time; the system being characterised in that it is configured to further execute computer program code to: iii) for all pairings of the sensors having a transient pressure event occurrence, determine, from the data repository, routes in the pipeline network between the sensors of the sensor pairing; iv) determine, for each route and in dependence on difference in timestamps of the respective sensors, a potential source location in the pipeline network for the transient pressure event; v) perform a simulated transient event for each potential source location and determine a modelled arrival time of a transient corresponding to the event at each of the at least two sensors; vi) compare the timestamp of the event occurrence for each of the at least two sensors with the modelled arrival time and selecting the potential source location corresponding to the closest modelled arrival time. iii) for all pairings of the sensors having a transient pressure event occurrence, determine, from the data repository, routes in the pipeline network between the sensors of the sensor pairing; iv) determine, for each route and in dependence on difference in timestamps of the respective sensors, a potential source location in the pipeline network for the transient pressure event; v) perform a simulated transient event for each potential source location and determine a modelled arrival time of a transient corresponding to the event at each of the at least two sensors; vi) compare the timestamp of the event occurrence for each of the at least two sensors with the modelled arrival time and selecting the potential source location corresponding to the closest modelled arrival time.