Digitalization and the Role of the PERTE Program in the Transformation of the Integrated Water Cycle Sector.

This article analyzes the digitalization of the integrated water cycle in Spain, driven mainly by the Water Cycle Digitalization PERTE program. It examines the conceptual foundations of digital transformation in the water sector — from data architecture and interoperability to digital twins, distinguishing them from static BIM/GIS models — as well as the maturity levels operators must reach to deploy AI and predictive tools reliably. Through real-world case studies (drinking-water supply, distribution networks, wastewater treatment, river basin authorities, urban sanitation, and BIM implementation in dams), it draws cross-cutting lessons on interoperability, data governance, and organizational adoption. The article closes with a critical assessment of the PERTE program's achievements and pending challenges, concluding that digitalization must serve verifiable operational results and human decision-making rather than technology accumulation for its own sake.