Peccadilloes of Water Quality

Saturday is always a laid-back day for me, so forgive me for not popping something up, earlier. As my wife Cathy prepares hamburgers on pretzel buns I thought I would talk a bit about some of the weird facts about water quality.

What adjectives come to mind when you visualize an I.V. bag attached to a hospital patient? Pure, clean, sanitary, clinical, and critical are the kind of adjectives that come into my mind. I am sure that you have similar thoughts. So what would you think if I told you that water in I.V. bags, and inject-able pharmaceuticals is considered dirty for the manufacturing of windshields, colorized aluminum keys, automobiles, and even flatware?Injection

Ir’s actually true. The United States Pharmacopoeia (USP) standards for WFI (water for injection), categories 23, 24 and 27 water call for an electrical conductivity of 1.3 μs/cm (microseconds per centimeter). For ease of comparison, we will convert this to roughly 1 megohm on the resistivity scale. Conversely, the electronics industry calls for something called E1 grade water which is 18 megohm quality.

So why would the electronics industry, even the glass, aluminum and auto industry need water that is 18 times more pure than the pharmaceutical industry?

The answer is what most people call water spots. As we learned elsewhere in this blog, the spots left behind by contaminated water are actually metals such as sodium, calcium, potassium, iron and more. These metals conduct electricity. So for instance, when making a microprocessor, many of the electrical pathways inside the chip are so minute that they can only be seen by microscopy. It is imperative then, that in the rinsing process the water dry completely spotless for you see one little “water spot” which conducts electricity, could ruin chip production by causing a short across the many pathways that the “water spot” touched. The deposits left behind by “spotting” likewise ruin glass production and decorative metal production, as well as the adhesion of the electro-coating paint process used in the automotive industry.

Now don’t get your canteens all in a bunch, because I never said water for injection was dirty. Trust me, your I.V. bags and injectable drugs are more than safe. I just though I would give a little perspective to what water purity actually means.