International Journal of Civil, Mechanical and Energy Science, 8(1) Jan-Feb, 2022 Available: https://aipublications.com/ijcmes/ Peer-Reviewed Journal ISSN: 2455-5304 https://dx.doi.org/10.22161/ijcmes.81.1 1 Analysis of Water Quality Characteristics in Distribution Networks Raber Hamad 1 , Mehmet İshak Yüce 2 Department of Civil Engineering, Gaziantep University, Gaziantep, Turkey 1 Email: rabar_hussen@hotmail.com 2 Email : yuce@gantep.edu.tr Received: 03 Jan 2022; Received in revised form: 11 Feb 2021; Accepted: 20 Feb 2022; Available online: 03 Mar 2022 ©2022 The Author(s). Published by Infogain Publications. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) Abstract— In this study, a model was developed by Epanet2.0 software to analyze water quality for parameters of hydraulic and water quality model (chlorine concentration and water age model) for a segment of Erbil city WDS by using observed and documented data. Controlling free residual chlorine properly is important to ensure meeting regulatory requirements and satisfying customer needs. For the calibration process and collecting field data digital pressure loggers for recording pressure in a WDS was installed. For discharge measurements, ultrasonic flow meters were used. To assure the reliability of the model a calibration process was carried out for extended period analysis and several alternatives had been studied as a solution to overcome negative pressure zones by the calculated Hazen William C-factor. This kind of study can be used to predict so many infrastructure projects. Keywords— Water Quality, Water Distribution system, Calibration, Chlorine Concentration, Water age. I. INTRODUCTION drinking water utilities face the challenge of supplying drinking water to their users despite the many factors that can result in the retrogression of water quality before it is delivered to the user’s tap. Frequently, raw water is derived from groundwater sources that may be subject to naturally occurring or accidental contamination (ILSI 1999, Gullick et al. 2003). The first Proposition of using mathematical models to analyze water distribution systems was in 1930 s by Hardy Cross (1936). water quality models have reached operational status, but research and development continue to further the understanding of the processes taking place in the distribution system and to translate this understanding into usable tools (i.e. Epanet2.0 program).In studying water distribution system the most important thing which has apriority to determine the type of model that is most applicable because so many factors have an impact on the degree of temporal ( overtime ) for example, steady-state modeling represents external forces as constant in time (static) and determines solutions that would occur if the system were allowed to reach equilibrium (Wood 1980a). In dynamic modeling, demands and supplies are allowed to vary with time and the resulting temporal solution is determined (Clark et al. 1988a, Clark et al. 1988b). After the hard efforts of researchers to computerize both water quality and Hydraulic models finally in 1993 EPANET2.0 was initially developed in the united states by the Environmental protection agency as a distribution system hydraulic-water quality model to support research efforts at EPA (Rossman et al., 1994). The development of the EPANET software has also convinced the requirement for an acquisitive public-sector model and has served as the hydraulic and water quality “engine” for many scientific and commercial water quality models. Water age is considered as a time to convey particles of water or time to travel water particles from the source (after the treatment process) to the consumer’s tap. There are two reasons behind studying water age, firstly to ensure the contact time with chlorine secondly, to avoid quality deterioration with time. Water age varies according to the fluctuation of demand in a model. To estimate water age in a water distribution system a mathematical model that represents the hydraulic behavior of the movement of water has been used. (Clark and Grayman, 1998). In the mid-1980s a Single period analysis travel time models were first