Techniques for producing ultra-pure water include using a combination of charcoal filters, reverse osmosis (RO), and deionization (DI) columns, achieving around 10 megaohm-cm purity. The theoretical maximum purity is approximately 18 megaohm-cm, which can be approached with a high-quality DI unit. Multiple-stage distillation is suggested as a potential method for achieving ultra-pure water, though it has limitations, such as the inability to remove chlorine effectively. There is interest in researching issues related to ultrapure water (UPW) storage and transport, as well as the erosion of materials in contact with UPW. Overall, achieving ultra-pure water requires a careful selection of techniques and equipment.