Assessment of Inflow and Infiltration in Sewers: Case Study of Antalya, Türkiye

Unwanted inflow and infiltration (I/I) of rainfall and groundwater into urban sewer systems are a critical issue for sustainable water management. This study examines the data from the two largest and most representative wastewater treatment plants (WWTPs) in central Antalya, Lara and Hurma, which both have large service areas and diverse hydrological conditions and infrastructural characteristics. By analysing data from 2016–2019, the study explored various standards and methods, including empirical equations, to quantify I/I levels. Results indicate that I/I contributed between 40.4% and 94.3% to wastewater flow during the period. Additionally, I/I was calculated as 0.8 and 1.3 m 3 /day‐ha for Lara and Hurma WWTPs, respectively. Overall, the findings not only demonstrate the deficiency of existing collection systems in Antalya but also show the strategic value of applying comparative I/I assessment methods to develop a framework that can support more resilient wastewater management strategies in fast urbanizing regions worldwide.