What does it mean to say that water autoionizes? View Available Hint(s) What does it mean to say that water autoionizes? Water will cause many ionic compounds to dissociate without additional input of energy. Water is a good conductor of electricity; and when it conducts, it ionizes. Water is polar, similar to an ion being polar. Therefore, it is autoionic. A water molecule can donate a proton to another water molecule, forming H3O+ and OH− in solution.