The main goal of water treatment is to avoid human health risks and to provide sufficient and good quality water for drinking, industrial purposes, and other economic activities by removing chemical and biological contaminants through water treatment processes. However, these processes require increasing efforts in terms of technology, chemicals and energy inputs, which translates to increased secondary environmental impacts and increased water production costs. The objective of the study is to evaluate the drinking water treatment (DWT) system in Iasi City (Romania), by means of life cycle assessment and to identify and characterize the environmental impacts, to determine the weak points of drinking water production processes. Iasi City is the most developed urban centre from Moldova Region in the North Eastern region of Romania and has a DWT system providing water in accordance with European standards. The DWT system process comprises the following stages: coagulation/flocculation with ferric chloride (or polyacrylamide and powdered activated carbon) coupled with pre-oxidation (injection of chlorine dioxide), followed by sedimentation in radial basins, pH correction with calcium hydroxide, rapid filtration on sand filters, slow filtration on granular activated carbon (GAC) filters and followed by final disinfection with chlorine gas. In this study a life cycle analysis has been applied to assess the environmental performance of Iasi DWTP for 1 m3 of potable water produced, considering the impact generated by energy consumption, technologies and reagents used. The electricity required by the different treatment stages has been accounted for the entire DWT plant, each equipment and water treatment parameters being monitored and controlled through a SCADA software. The main contributors to impact in most of the categories are the electricity consumption and the iron chloride production used in coagulation/flocculation step. The most important impact categories are the freshwater eutrophication and the freshwater and marine ecotoxicity, and the most important contributors remain electricity and iron chloride usage. The level of detail obtained for the inventory and the impact assessment steps may be used as reference for future LCA studies, analysing other water treatment plants since the climate, technological, cultural and socio-economical differences clearly define the particularities of a DWT in any context and region
