why is water rarely available in pure form ?

Water is called the universal solvent because it can dissolve most substances in loarge amounts. Because of this, water is rarely found in its pure form.

(Precipitation absorbs carbon dioxide and other gases, as well as traces of organic and inorganic material from the atmosphere. Because water reacts with minerals in the soil and rocks, surface and groundwater may contain many different dissolved substances. Surface waters may also contain domestic sewage and industrial wastes. Groundwater from shallow wells may contain nitrogen compounds and chlorides, but water from deep wells generally contains only dissolved minerals. Seawater contains many soluble compounds in addition to salt.)