A simple comparison of water hardness between tap water and purified water using a soap test

This project presents a qualitative experimental comparison of water hardness between treated (purified) water and municipal tap water. The experiment was based on observing foam formation after agitation, as an indicator of relative water hardness. No quantitative measurements were performed; instead, differences in foam formation were used to identify which water sample exhibited higher hardness. This study was conducted as an independent student experiment to demonstrate basic concepts of water hardness and water quality.