Why Patton's and reeder's reagent is not used for the determination of total hardness of water?

Patton's and Reeder's reagent is not used for determining total hardness of water because it specifically measures only calcium and magnesium ions, which are components of hardness but not the totality of it. Total hardness includes all divalent and trivalent cations, and relying solely on this reagent could overlook other contributing ions. Additionally, the method may not provide accurate results in the presence of other complexing agents or in varying pH conditions, limiting its applicability for comprehensive hardness assessment.