There are different types of pure water but two among the most commercially popular are distilled and deionized water. Generally they are the same in the sense that both don’t contain ions and minerals and are essentially just water. Nonetheless, the maintenance of their quality depends on how buyers store them.
Many people don’t understand what deionized or DI water is and often compares it to other bottled water in grocery stores. But this type of liquid is not like typical commercial one sold at shops. Usually you may find bottled distilled water sold commercially and they are the alternative. DI water is also called demineralized water and the term suggests it is different from bottled mineral one.
Water that is demineralized is the purest form available in the market. Water companies purify it to an extent that it becomes deionized. Many companies use this kind of water in manufacturing and maintenance. For instance, cleaning of equipment may require the use of pure water during the final rinse. Chemical laboratories also use the same in cleaning glassware because using ordinary water produces scales and spots.
The removal of ions is a tough process relying on equipment, which is called resin beds. In sophisticated deionization process, water passes through two resin beds, one to remove positive ions (Ca++, Mg++, Fe+++, and K+) and the next to remove negative ions (Cl-, sulphates, and carbonates). Of course, not all the ions are removed but almost all ions are lost after the process. The process, thus, results to the purest form of water existing in the planet.
The best way to test for water quality is by running conductivity and resistivity tests. These two tests provide data on how the water sample conducts and resists electricity. Since ions are electric conductors, their presence in the liquid raises conductivity levels. Meaning, if you pass electricity in plain water, it can conduct electricity. Pure water in itself is a non-conducting covalent substance.
Therefore, the lower the conductivity, the lower the ionic content of the liquid. The highest quality DI water gives the lowest conductivity readings. Consequently, it should give high resistivity readings. Conductivity and resistivity are generally employed in testing the quality of DI water. But these tests cannot determine the presence of organic substances.
Water deionization only removes charged particles and does not remove organic solutes which are uncharged. Some people think that this inability of the process to remove impurities other than ions makes it inefficient. However, deionization is not a process employed for any raw water. Companies run raw water to various filtration methods to remove sediments, organics, and microorganisms before passing it through ion exchange resin beds.
Different manufacturers buy deionized water in bulk to save cost of shipment or transportation. Many homeowners also do the same thing.