Abstract The objective of the present study to assess the performance of a suggested sewer line by using pipe jacking system (PJS) in order to enhance the sewage capacity and mitigate sewer flooding of historic pilgrimage city of Karbala, Iraq. The storm water management model (SWMM5) was used for this purpose. The simulation of exiting sewer system reveals that sewer discharge during peak pilgrimage period is more than 200% of the capacity of existing sewer line. Installation of SLL having a diameter of 2.5 m at a depth ranging between 12 and 22 m by PJS can reduce water depth in sewer pipe by 78%. The reduction of water depth at sewer pipe can reduce sewer overflow up to 70%, if the system is installed and managed properly. The methodology proposed in the paper can be applied in any location having similar problem with necessary modifications.