Najaf city has adopted the separate sewerage network system, similar to other Iraqi cities, due to its almost dry climate. The city’s population has grown at a relatively high annual rate of 11.6%, largely due to significant migration. This growth led to an expansion of the city’s master plan by about 150% in area in 2009 compared to 2003. There is no recent research addressing the shortage of sewerage services in Najaf, which justifies the need for this study. Population estimates for the years 2003–2018 were obtained, and archival aerial photographs of the city from the same period were used to assess the city’s growth and the length of sewerage network required. From 2008 to 2018, there was a strong response to serve the rapidly growing population, with the proportion of people served increasing from 17.8% to 84%. However, slum areas, which account for about 20% of the city’s area, and residential complexes, covering 17% of the city, have not yet been served. The city’s planned expansion will increase its area by 180%, which will require approximately double the capacity of the current sewerage system.