There are several different parameters that people use to gauge or rate purity. What is pure for one application, may be unsuitable for another. For instance, water in a medical IV bag would be considered “dirty” in the electronics industry.
Water purity is typically measured by the parameters of ionic/dissolved solids, sediment, color, bacteria, volatile organics/carcinogens and overall organics. One of the most popular ways to gauge water quality is to measure either the resistance, or conductivity of electricity through the water. This is done by passing an electrical current through two points and using an instrument that measures how easy the current passes through the water.
Resistance, the ohm (Ω) is a very common unit of measurement. That said, let’s take a look at some comparisons.
- Totally pure water – 18,000,000 ohms
- Distilled water – 200,000 ohms
- Cleveland Ohio City Water 2,500 ohms
As you can see, distilled water, which many consider to be the gold standard of water purity, is not a pure as one might think. However, when we look at a typical city tap water, like Cleveland, Ohio, we see that distilled water is quite a bit more pure.
Water purity; it’s purely relative!