Creber, KJ & Correia, LDC 2026, 'The importance of transient analysis in successful design and operation of underground paste distribution systems', in AB Fourie, M Horta, M Oliveira & S Wilson (eds), Paste 2026: Proceedings of the 28th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 1-11, https://doi.org/10.36487/ACG_repo/2655_56 (https://papers.acg.uwa.edu.au/p/2655_56_Creber/) Abstract: The initial design of a paste underground distribution system (UDS) traditionally relies on steady-state hydraulic analyses to specify the piping. While this approach offers a useful baseline, it often fails to capture the full range of operating conditions encountered in practice. Transient events, such as paste pump trips, pipeline filling, pipe blockages and ruptures, and poor operator control, will introduce pressure surges that may compromise system integrity, safety, and operability. This paper highlights the importance of incorporating transient analysis into the design phase of paste backfill distribution systems, particularly for complex networks with multiple discharge locations, elevation changes, or long pipe runs. Using case studies and simulation results, the paper demonstrates how transient modelling identifies vulnerabilities in the design not apparent under steady-state conditions. Once potential flaws in a design have been identified, the analysis can guide the selection of mitigation strategies, including, but not limited to, appropriate pipe specification, adequately sized pipe supports, and ensuring operators run the paste UDS at the correct operating conditions. In addition to protecting the UDS, transient analysis supports robust commissioning planning and reduces the likelihood of costly downtime or system failure post-implementation. The discussion is centred around the practical challenges and lessons learned from recent paste backfill projects, reinforcing that transient analysis should be regarded not as an optional consideration, but as a critical component of responsible UDS design. Keywords: paste transport, underground distribution system, hydraulic modelling, transient analysis, safety