Water that "lathers easily with soap" is said to be soft water. Hard water requires more soap to produce lather. This is because hard water contains compounds that react with soap to create scum. To remember this, just think of the working song from Enchanted and Giselle says: "soapy scum". Don't ever mix scum with scale. Soapless detergents don't react with hard water to form this.
This occurs if the water has sometime been in contact with rocks and dissolves magnesium and calcium ions.
Temporary hard water produces scale, which stays in boilers, pipes and kettles. On the other hand, calcium compounds are good for our health, give us strong bones and reduce the risk of heart disease.
Soft water is the complete opposite. Although it may have dissolved substances, it doesn't contain magnesium ions, calcium ions or any other salts that cause scum and scale. You can simply remove these ions and other salts from hard water to make soft water.
However, although temporary hard water causes scale, permanent hard water doesn't because it doesn't soften when heated. This…