Think of water purity like a grading system, from a D- to an A+. Tap water is a solid C. Distilled water? That’s a B. Type I water, often called ultrapure water, is the gold medalist. It has almost zero contaminants—no minerals, no bacteria, no dissolved gasses, nothing.
Scientists measure this by resistivity, which sounds fancy but is simple: pure water doesn’t conduct electricity well. Type I water hits a stunning 18.2 megohm-cm resistivity. That’s basically the water equivalent of a zen monk—calm, clear, and completely uncontaminated.
