Sustainable water management is essential in urban environments, but it poses challenges with unclear pathways for improvement. This paper presents findings from a comprehensive diagnostic of the water management in the urban green infrastructure of the Porto Metropolitan Plan (PMA). The main goal was to understand the knowledge, interest and preparedness level of the 17 integrating municipalities in embracing water conservation measures. As part of this effort, an online questionnaire was developed and made available for response from February 15 to March 15, 2023. An analysis of the questionnaire responses revealed that three-quarters of municipalities have appropriately categorised their urban green infrastructure. However, six municipalities lack insight into the extent of irrigated Urban Green Spaces (UGS). While municipalities demonstrate attentiveness towards plant water requirements and the significance of utilising indigenous species for vegetation management, replacing irrigated lawns with alternatives remains uncommon. Only two municipalities explicitly employ smart or efficient irrigation, although five partially use such systems. At the municipal scale, the results reveal that one of the least implemented measures is adopting natural-based solutions for rainwater harvesting and storage. Another significant result is that only three municipalities exhibit awareness of their total available water volume. Additionally, over half of the water used to irrigate UGS is potable. Overall, these insights paint a comprehensive picture of water management within the PMA region, enabling tailored recommendations to address the specific needs of each municipality.