ABSTRACT Various industries involve interconnected coupled tank systems to control fluid level, which poses significant challenge for traditional controllers. A tilt-integral-derivative controller offers enhanced adaptability for such systems. However, tuning of these controllers is highly challenging. This work focuses on enhancing the liquid level control in coupled tank systems using a tilt-integral-derivative controller. Tuning for the control algorithm is achieved through the application of Harris's hawks optimization. An objective function is designed by imposing constraints on performance metrics such as integral square error, integral absolute error, integral time absolute error, and closed-loop gain, which are then solved using Harris's hawks optimization. Further, the robust behaviour of the system is exhibited using μ-analysis to assess its stability. Simulation studies confirm the control algorithm's effectiveness, showing superior performance in reducing settling-time and minimizing overshoot. Additionally, the robustness of the controller in handling sensor and actuator faults under varying operating conditions is demonstrated.