Water is called the "universal solvent" because it can dissolve more elements than any other liquid.
More Info: You probably learned in science class that the chemical formula for water is H2O, and that a water molecule is formed when two hydrogen atoms, sharing a pair of electrons, connect with an oxygen atom having a pair of electrons that are not shared. The hydrogen is positive while the oxygen is negative, and because of this polarity, water has the capacity to dissolve virtually all substances, whether they are good or bad, positive or negative.
What Water Can Do
Because of these positive and negative charges, water molecules have a tendency to attract each other and adhere to each other, forming clumps, and we use the term "drops of water" because of this. In addition, if gravity and certain other forces of planet Earth were not a factor, drops of water would be perfect spheres and shaped like a ball. This means that they would be far less likely to "stick" together, and water would be far less beneficial as a solvent.
Water is referred to as the "universal solvent" precisely because it can dissolve more elements than any other liquid. As a result, whether water travels through the human body or through the ground, it transmits a variety minerals, nutrients, and chemicals. Also, when it is free of all impurities, water has a neutral pH reading of 7, indicating that it is neither basic nor acidic, which is the reason that it is so effective as a solvent.
The Importance of Hydrogen Bonding
Many of water's unique characteristics are due to what scientists call "hydrogen bonds". For instance, ice, which is a solid, will float because hydrogen bonds keep the water molecules further apart than they do with water in its liquid form, which contains one less hydrogen bond in every molecule. In addition, water's surface tension, high heat for vaporization, and ability to act as a virtually universal solvent are all the result of the hydrogen bonding that takes place.