No, ion exchange processes can’t purify drinking water. Ion exchange systems can be used to remove select contaminants from water, but ion exchangers aren’t capable of removing all contaminants from water. So, you can selectively filter water with ion exchange resins, but you can’t remove all total dissolved solids from water. High levels of TDS can actually damage an ion exchange system, and pre-treatment filtration may be required before ion exchange to prevent resin fouling.