I think the final say so should be by a hand-to-hand voltage test. Your body produces voltage and electric current and the electrical system that does that is dependent on minerals (electrolytes such as sodium, potassium, chloride, calcium, and phosphate). If you start to drink distilled water and after a month or two your personal voltage declines then I'd say your diet is deficient enough that you need to also take mineral supplements.
(Be sure to lick your fingers before holding onto the voltmeter probe leads.)
I'm doing this now so hope to report back with some news.