Bentonite–sand mixtures are critical components in containment systems, where their hydraulic behavior plays a crucial role in the overall performance of these systems. This study explores the impact of sand content and moisture variations on the hydraulic properties of Bentonite–Sand mixtures. Laboratory tests were conducted on two different mixtures to evaluate their hydraulic conductivity and unconfined compressive strength under varying moisture conditions. The findings reveal that both sand and moisture content significantly influence the hydraulic behavior of these mixtures. The variations are vital for optimizing Bentonite–Sand mixtures for different containment applications, ensuring they meet performance requirements under diverse moisture conditions. Additionally, a numerical study was performed to simulate the hydraulic performance of these mixtures as liner materials, providing a predictive tool that aligns with the laboratory results. This research highlights the importance of accounting for sand content and moisture variations in Bentonite–Sand mixtures to ensure effective containment performance, particularly in applications requiring precise permeability control and structural stability.