What has to be true of a substance for it to dissolve in water?

The polarity of a water molecule comes from the uneven distribution of electron density of hydrogen and oxygen atom. The oxygen in the water molecule is more electronegative than the hydrogen. Water has a partial positive charge near the hydrogen atom and a partial negative charge near the oxygen atom. The result of this electrostatic attraction results in the bond called hydrogen bond. Also, because of this bond, it has the ability to dissolve most of the solutes due to its polarity and bonding.