For the problem of set point regulation of the liquid level in coupled tank systems,we present a continuous sliding mode control (SMC) with a conditional integrator,which only provides integral action inside the boundary layer.For a special choice of the controller parameters,our design can be viewed as a PID controller with anti-windup and achieves robust regulation.The proposed controller recovers the transient response performance without control chattering.Both full-state feedback as well as output-feedback designs are presented in this work.Our output-feedback design uses a high-gain observer (HGO) which recovers the performance of a state-feedback design where plant parameters are assumed to be known.We consider both interacting as well as non-interacting tanks and analytical results for stability and transient performance are presented in both the cases.The proposed controller continuous SMC with conditional integrators (CSMCCI) provides superior results in terms of the performance measures as well as performance indices than ideal SMC,continuous SMC (CSMC) and continuous SMC with conventional integrator (CSMCI).Experimental results demonstrate good tracking performance in spite of unmodeled dynamics and disturbances.