Analysis of institutional work on innovation trajectories in water infrastructure systems of Melbourne, Australia

• Transitions studies require deeper insight into the institutional structuring processes implemented by actors.
• We map the institutional work supporting the maturing of innovations in three empirical cases of Melbourne's water system.
• The cases had different institutional alignments with the established regime and trajectories for key stages of maturity.
• Trajectories are characterised by: speed; purpose and type of institutional work; limiting conditions for further maturity.
• We derive hypotheses on the linkage between institutional work and innovation maturation from cross-case comparison.

Infrastructure systems are facing sustainability challenges but are locked into their current practices. Transitions studies aims to understand trajectories towards new socio-technical regimes and argue for agency-centric perspectives to explain processes of change. This paper adopts an institutional lens, examining the institutional creation processes needed for maturing innovations within established systems. Three innovations in Melbourne's water system were selected as empirical cases: desalination, wastewater recycling and stormwater harvesting. Each had a different institutional alignment with the established regime and different trajectories between key stages of maturity, from pre-niche to niche, niche-regime and regime. The paper examines the purposes and types of institutional work undertaken to support each stage: cultural-cognitive, normative and regulative. Their trajectories were influenced by the regime alignment and characterised by maturation speed, institutional work undertaken and limiting conditions for further maturation. Cross-case comparison enabled derivation of hypotheses on the linkage between institutional work and innovation maturity.