Distilled water and filtered water are two common types of purified water, often leading to confusion regarding their differences and optimal uses. Understanding their purification processes, the substances they remove, and their resulting characteristics is important for making informed decisions about water consumption and application.
Understanding Distilled Water
Distilled water undergoes a purification process involving boiling and condensation. Water is heated to its boiling point, transforming into steam and leaving behind impurities such as minerals, contaminants, and microorganisms. This steam is then collected and cooled, condensing back into a liquid state as highly purified water.
The distillation process effectively removes a broad range of inorganic compounds like lead, iron, calcium, and magnesium, along with nitrates and sodium. It also inactivates or removes bacteria, viruses, and other microorganisms, making the water nearly 99.9% pure. However, some organic compounds with boiling points similar to or lower than water, such as certain volatile solvents, may not be completely removed.
The resulting distilled water has virtually no dissolved minerals. Many describe its taste as “flat” or “bland” due to this absence of minerals and dissolved gases, which typically contribute to water’s flavor. Its electrical conductivity is very low, indicating minimal dissolved solids, and its pH is typically neutral to slightly acidic after exposure to air.
Understanding Filtered Water
Filtered water is produced by passing water through various physical, chemical, or biological barriers designed to remove impurities. The effectiveness and specific contaminants targeted depend on the type of filtration method employed. Common filtration techniques include activated carbon filters, reverse osmosis (RO) systems, and sediment filters.
Activated carbon filters are effective at adsorbing chlorine, volatile organic compounds (VOCs), and other chemicals that can affect water’s taste and odor. Reverse osmosis utilizes a semi-permeable membrane to remove a wider range of contaminants, including dissolved solids, heavy metals like lead and mercury, and some bacteria and viruses. Sediment filters, often used as a preliminary step, trap larger particles such as sand, rust, and debris.
Unlike distillation, many filtration methods are designed to retain beneficial minerals naturally present in water. This retention of minerals contributes to filtered water often having a cleaner, crisper, and more natural taste compared to unfiltered tap water. The overall purity of filtered water varies significantly based on the specific filtration system.
Distinctions and Practical Uses
Distilled and filtered water differ significantly in their purity levels and mineral content. Distilled water is characterized by its extreme purity, with virtually all minerals, impurities, and microorganisms removed. Filtered water, conversely, varies in its purity depending on the filtration method, typically removing harmful contaminants while often retaining beneficial minerals.
These differences impact their taste. Distilled water is often described as flat or bland due to its lack of dissolved solids. Filtered water, by contrast, generally offers an improved taste because it removes undesirable elements like chlorine, while retaining minerals that contribute to a more natural flavor.
The production process for distilled water, involving boiling and cooling, is often energy-intensive, making home distillation systems less common for everyday drinking water needs. Filtered water systems, such as pitchers or under-sink units, are generally more accessible and cost-effective for daily use.
Distilled water is preferred in settings where mineral-free water is essential to prevent buildup or interference. This includes medical applications for sterilizing equipment and cleaning wounds, laboratory use for preparing solutions and cleaning glassware, and in appliances like car batteries, steam irons, humidifiers, and CPAP machines. Its purity ensures that no mineral deposits form and that sensitive chemical reactions or medical procedures are not compromised by impurities.
Filtered water is widely used for general drinking and culinary purposes. Its ability to remove common contaminants while preserving naturally occurring minerals makes it a popular choice for daily hydration. When used for cooking, filtered water can enhance food flavors by eliminating substances like chlorine that might impart off-tastes to meals or beverages such as coffee and tea. This balance of contaminant reduction and mineral retention makes filtered water suitable for everyday consumption and food preparation.