Answer. Soft water is that which produced good lather with soap. While hard water is that which does not produce lather with soap?
Hard water consists of salts of divalent cations like Mg2+, Ca2+, and anions like Cl-, SO42- ,HCO3- and CO32- for example, gypsum (CaSO4.2H2O) and limestone (CaCO3) in water while soft water contains these salts.