Thermal storage water tanks are recognized as an effective means to enhance the stability and efficiency of energy systems. However, in large-scale applications, the construction cost of these water storage tanks often represents a substantial portion of the total investment in compressed air energy storage (CAES) systems. To tackle this issue, a novel multi-tank layout design is proposed with the aim of reducing storage-related expenses. An equilibrium thermodynamic model is developed to assess the synchronization of temperature, pressure and water-level variations among the tanks. Simulation results based on a two-tank configuration reveal that the gas zone connection plays a crucial role in achieving synchronous variations across the tanks. Moreover, the study investigates the feasibility of increasing the number of tanks within a single block. To this effect, three configurations are evaluated over three complete charging–discharging cycles: 12 blocks with 2 tanks each, 8 blocks with 3 tanks each and 6 blocks with 4 tanks each. The results demonstrate that enlarging the connection pipe diameter is essential to preserve water level synchronization as the number of tanks within a block increases.