Rethinking water reuse for climate adaptation in Apulia, Italy: From plant-level to system-wide strategies

Study region: The Apulian Aqueduct (Acquedotto Pugliese) is Italy’s largest water distribution system, supplying urban, industrial, and agricultural users across the Apulia region in southern Italy. Apulia is characterized by a predominantly semi-arid Mediterranean climate, where limited local water availability and recurrent droughts exacerbate competition among sectors.Study focus: This study presents a decision-analytic framework (DAF) for the design of Pareto-efficient, system-wide water portfolios that integrate conventional management and reuse technologies. The DAF jointly evaluates water allocation, reservoir operation, and reuse deployment under historical conditions and four future scenarios combining climate conditions (RCP 4.5 and 8.5) and socio-economic projections.New hydrological insights for the region: Under future projections, decreasing water availability and growing drinking water demand are expected to intensify conflicts among sectors, challenging the system’s capacity to meet supply needs. Historically, irrigation and industrial deficits averaged 56.8 Mm3/year and drinking water deficits 31.4 Mm3/year. In the most extreme climate scenario (RCP 8.5, 2090–2099), these increase to 180.4 Mm3/year (+218%) and 185.9 Mm3/year (+492%), respectively. Implementing water reuse reduces irrigation and industrial deficits by 29.3 Mm3/year and drinking deficits by 15.7 Mm3/year, yet remains far from restoring historical performance. These results demonstrate that while reuse technologies offer meaningful relief, only coordinated, large-scale adaptation strategies can ensure the long-term resilience of Apulia’s water system under future climatic stress.