<p>Rainwater harvesting is a viable and sustainable approach to water conservation, particularly in light of increasing water scarcity and environmental pressures. However, its effective uptake continues to be uneven, often shaped by the beliefs and attitudes of local councils, which serve as key actors in policy development, enforcement and public accountability. This paper explores the intricate relationship between local councils’ belief systems and attitudes towards rainwater harvesting, offering insight into stakeholder-related factors that shape environmental behaviour and impact implementation fidelity. Drawing on the theory of planned behaviour, this paper highlights how perceived behavioural control and attitudes within the organisational setting reinforce or weaken commitment to policy adherence. Qualitative data at the organisational level were collected through semi-structured interviews, document reviews and site observations, and subsequently analysed thematically in relation to participants’ beliefs, attitudes and behaviours in performing their duties. Four interrelated sub-themes emerged: (1) financial constraints, (2) government administration practices, (3) environmental beliefs and (4) homeowners’ attitudes. The findings reveal that institutional scepticism toward rainwater harvesting was partly shaped by the experiences and feedback of homeowners and developers, which undermined councils’ confidence and weakened enforcement. Conversely, councils with strong environmental beliefs recognised the long-term benefits of rainwater harvesting and demonstrated higher implementation fidelity, thereby strengthening public trust and stakeholder confidence. By uncovering the feedback relationship between belief systems, administrative behaviour and policy adherence, this paper advances conceptual understanding of the challenges confronting local environmental governance.</p>