This study investigates the surface tension behavior of several aqueous systems—including pure water, salt solutions, detergent solutions, and mixed detergent–salt systems—by employing the capillary rise method as a diagnostic tool. Experimental results demonstrate that a transition in capillary height occurs as the solute type changes, reflecting variations in cohesive forces within the liquid phase. Pure water consistently exhibits the highest capillary rise due to its strong hydrogen-bond network, whereas the introduction of surfactants significantly lowers the surface tension, resulting in a marked decrease in capillary height. Salt solutions show moderate and ion-specific effects, while mixed detergent–salt systems display more complex behavior due to competitive adsorption at the air–water interface. Analysis of the data confirms that the capillary rise method is sensitive to interfacial modifications caused by both surfactants and electrolytes. These findings align with recent research on interfacial thermodynamics and demonstrate that solute identity plays a key role in determining liquid surface tension. The study provides important insights applicable to detergent formulation, cleaning processes, colloidal stability, and the design of interfacial materials.