When you boil water, the pure water vapor rises, but the ions—being bigger and heavier—stay behind in the pot. It’s like when you let a pot of pasta water boil over; the water escapes, but the salt stays put. That leftover gunk in your kettle? Those are the ions you don't want in your distilled water.
So when that steam is collected and cooled, you get water that’s H₂O and nothing else. No calcium to help your bones, no magnesium for your muscles—just pure, naked water molecules.
This is why some folks joke that distilled water is “boring water.” It has no personality. But for certain jobs, boring is actually brilliant.
