<p>This paper presents the design of terminal sliding mode control (TSMC) and fast terminal sliding mode control (FTSMC) strategies, integrated with an adaptive law, to control liquid levels in a coupled tank system. The adaptive law provides a dynamic alternative to static switching control coefficients by employing a self-updating parameter structure throughout the control process. The selection of appropriate control gains for classical sliding mode control (SMC) and its variants remains a significant challenge. To address this issue, the adaptive approach not only simplifies the gain selection but also helps reduce the substantial chattering typically observed in control signals. The stability of the design methodologies is proven using the Lyapunov theory. The effectiveness of the proposed methods has been experimentally validated on a coupled tank system. The experimental results are compared with classical SMC, TSMC, and FTSMC approaches. These comparisons reveal that the proposed controllers, the adaptive terminal sliding mode control (ATSMC) and adaptive fast terminal sliding mode control (AFTSMC) methods achieve robust control performance and effectively minimize chattering in the control signal.</p>