A Combined Pile Raft Foundation (CPRF) is an innovative solution that integrates the load-distributing benefits of a raft with the load-bearing capacity of piles. The design of foundations for heavy loaded structures like water retaining structures, have unique challenges due to the substantial loads and dynamic forces especially in soft soil. Soil-Structure Interaction (SSI) is a key factor that determines the performance of foundations. The study highlights the necessity of incorporating SSI effects in foundation design to ensure accurate prediction of structural behaviour, for critical infrastructure and buildings. As part of the case study, it is proposed to do performance analysis of the structure with pile foundation (PF) and to compare it with the same structure after replacing the Pile Foundation with Combined Pile Raft Foundation (CPRF). The methodology involves modelling foundations for PF and CPRF by utilizing the program PLAXIS 3D and the SSI of the foundations can be analysed. This analysis provides valuable insights to optimize foundation design, contributing to the development of more strong and cost-effective foundation solutions and to maintain the operational safety of the structures.