All metals are capable of conducting electricity - they conduct because the atoms do not hold their electrons tightly when in large groups so the electrons (negatively charged subatomic particles) are free to move (throughout the atoms). Moving charge = electricity! The level of conductance is based upon their "willingness" to allow their electrons to move (sea of mobile electrons) 
Water (pure) does not conduct electricity - there is no freely moving charge (contains no charged particles). When ionic substances (salts) dissolve in water they dissociate into seperatre ions which are free to move about and therefore you have moving charge.