Ultrapure Water Is Not for Drinking
What is commonly referred to as “ultrapure” water goes beyond what is considered pure drinking water. In fact, it is not considered “fit” for human consumption. It is water so clean that it is used as an industrial solvent for cleaning semiconductors, producing pharmaceutical products. and for cooling in power plants.
Typical production of ultrapure water includes use of microfiltration membranes to remove particles from the water, ion exchange and reverse osmosis (RO) membranes to remove ions, UV light to kill bacteria and degassing membranes to remove dissolved oxygen.
We think of reverse osmosis, which can turn sea water into excellent drinking water, as taking “everything” out of water, but when it comes to water needed for many technical processes RO water isn’t even near clean enough. Ultrapure water requires 12 filtration steps beyond RO with the final filter having pores 20 nanometers in width. (Twenty nanometers is 0.02 microns.)