Deionized (DI) water is a highly purified form of water. It undergoes a process that removes dissolved mineral ions. This purification makes DI water exceptionally clean, suitable for specific applications where the presence of these ions would be detrimental.
What Deionized Water Is
Deionized water is water from which nearly all mineral ions, such as sodium, calcium, magnesium, iron, chlorides, and sulfates, have been removed. These ions are common in tap water and contribute to its “hardness” and conductivity. The primary method for producing deionized water is ion exchange, where water passes through specialized resin beads. These resins capture the undesirable positively charged ions and negatively charged ions, replacing them with hydrogen and hydroxyl ions, which then combine to form pure water.
This process differentiates DI water from distilled water. While distillation involves boiling water and condensing the steam, which removes minerals and organic matter, deionization specifically targets charged ions. Deionized water is characterized by extremely low conductivity and high resistivity, making it ideal for applications requiring water with minimal electrical interference.
Common Household Uses
Deionized water finds several practical applications around the home, primarily due to its inability to leave mineral deposits. Using DI water in steam irons prevents the buildup of limescale that can clog steam vents and shorten the appliance’s lifespan. The absence of minerals ensures that steam remains pure, avoiding stains on clothing. Similarly, humidifiers benefit from deionized water, as it eliminates the white mineral dust often seen when using tap water, preserving the humidifier’s efficiency and extending its operational life.
For cleaning tasks, deionized water is highly effective because it dries without leaving streaks or spots. This makes it a preferred choice for washing windows and car exteriors. Its purity also makes it suitable for car batteries, where mineral-free water is needed to prevent damage and ensure proper function.
Specialized Industry Applications
Industries rely heavily on deionized water where purity is paramount and even trace amounts of ions can cause significant problems. In semiconductor manufacturing, deionized water is essential for rinsing wafers and cleaning delicate components. Even minute impurities can cause defects in microchips, making ultrapure water a requirement for reliable and functional electronics.
The pharmaceutical industry uses deionized water extensively in drug and vaccine manufacturing, as well as for cleaning and sterilizing equipment. Its high purity ensures that no contaminants interfere with chemical reactions, compromise product quality, or affect the safety and efficacy of medicinal products. Laboratories also depend on deionized water for preparing solutions, conducting experiments, and cleaning glassware, where ion-free water prevents unwanted reactions and ensures accurate results.
Deionized water is also employed in power generation, particularly as boiler feed water, to prevent scale buildup and corrosion in boilers and turbines, which can reduce efficiency and cause costly damage. In the automotive sector, it is used in coolants and for diluting antifreeze to prevent mineral deposits in engines. Its applications span various fields, from cosmetics manufacturing to food processing, benefiting from its ability to prevent contamination and ensure product integrity.
Is Deionized Water Safe to Drink?
While deionized water is highly purified, it is not recommended for regular human consumption. The deionization process removes essential minerals like calcium, magnesium, and potassium that are naturally present in tap water. Consuming DI water exclusively could lead to a deficiency in these minerals.
Deionized water often tastes “flat” or bland due to the absence of dissolved minerals. Some sources suggest that deionized water, being chemically aggressive due to its lack of ions, may leach minerals from the body or even from plumbing pipes. It should not replace mineral-containing drinking water as a primary source of hydration. It is also important to note that deionization primarily removes ions and may not eliminate all organic compounds, bacteria, or viruses, meaning it is not necessarily sterile.