The Water Hardness Test is a laboratory procedure used to determine the hardness of water by measuring the total concentration of calcium and magnesium salts, expressed as calcium carbonate (CaCO₃). The test employs complexometric titration with EDTA, a chelating agent that forms stable complexes with metal ions. Through this experiment, students learn the principles of direct titration, complex formation reactions, and the significance of stability constants in analytical chemistry. The test also highlights the practical impacts of hard water, including scaling in pipes and appliances. Water hardness analysis is essential for water quality assessment in domestic, industrial, and environmental applications.