It's clear that you can't make water 100-percent clean, but what if you just did? Based on current water filtration technology, industrial reverse osmosis is as close to pure water as you can get, with a filtration rate of between 99 and 100 percent possible for most solids.
Nevertheless, take an expert's word for it when he or she tells you that you wouldn’t want pure water in your tap. The water that’s used to clean your iPhone is not something you’d want to drink as it can trigger hyper-hydration, acid reflux, diarrhea, and heartburn. Rather, water in its ultra-pure state is fit for industrial applications such as semiconductors and printing.
Although still not technically devoid of impurities, ultrapure water (UPW) is used to cut and clean electronic components like semiconductors. Ultrapure water’s resistance of 18.1 mega-ohms, compared to tap water’s meager 1,000 to 5,000 ohms, means there's hardly anything other than H2O in there. The lack of impurities also means it won't conduct electricity as well as ordinary water.
In addition, facilities that require UPW aren't your run-of-the-mill water filtration plants or beverage factories. Rather, these are mostly electronics companies that require pure water for the manufacture of microelectronics components, from production all the way to the cleaning and cooling stages.