One of the most common substances known to man is water. Water, if pure, is a colorless, odorless and tasteless liquid. It is a very good solvent for many substances, i.e., it can dissolve many substances, if not all, to an extent: this is why, chemically, there is no such thing as pure water.
Formation of water
Water is formed whenever two atoms (one molecule) of hydrogen combine chemically with one atom of oxygen.
Existence of water
Water could exist in three physical states: solid, liquid or gas. It is worthy of note that the three states can exist together in such a way that one state (phase) could be in contact with another. For example, if an ice block is placed inside a pot with a heating source at the bottom. The ice will melt and part of the melted ice will turn into vapor. In such a way, the ice block (solid) is in contact with the melted ice (liquid) and the vapor (gas). This is known as solid-liquid-gas contact.
Sources of water
Sources of water include : rain water, well water, river water, spring water, lake water, sea water, ocean, etc. The listed sources are known as natural sources of water. Out of the listed natural sources of water, the purest source is the rain water. All the natural sources depend on one another for replenishment. The rain water which is the purest form of natural water is formed as a result of vaporization of water from other sources such as the sea, river, lake, ocean, etc, and condensation of the vaporized water which later return back to earth as rain.
Rain water is the purest form of natural water because it is naturally distilled water. Water from other natural sources contains more impurities suspended inside it.
Treatment of water
Water is treated for special/specific purpose. The treatment of water is determined by the purpose for which it will be used for. Good examples of treated water are distilled water, reverse osmosis water, pipe born water, chlorinated water, ionized water, etc.,
Reverse osmosis water is a very pure form of a treated water. It is used for drinkable/ table water. Distilled water is the purest form of treated water. It is usually used in the laboratory for production of special chemical which requires very pure water. As it being said before, there is no such thing as absolute pure water. Water cannot exist in pure state because of its affinity to dissolve any substance its in contact with. It has been proven that there will always be certain amount of dissolve of whatever container which contains the water.