Tap water is sourced from local bodies like reservoirs or aquifers and treated by municipal systems to meet safety standards for public consumption. Distilled water, conversely, is a form of highly purified water created through a specific purification method designed to remove nearly all dissolved solids. The distinction between the two lies in their preparation methods and the resulting chemical composition.
How Tap Water is Treated and Distilled Water is Made
Tap water undergoes a multi-step municipal treatment process before distribution. The process begins with chemical addition, initiating coagulation and flocculation to bind small particles together. These larger clumps, or floc, are removed during sedimentation as they settle. The water is then passed through filters, such as beds of sand or gravel, to remove residual suspended matter. Treatment concludes with disinfection, typically using chlorine, to eradicate microorganisms. This process ensures biological safety while intentionally leaving in many naturally occurring minerals.
In contrast, distilled water is produced by a process that mimics the natural water cycle. The water is heated until it turns into steam, leaving behind virtually all non-volatile substances in the boiling chamber. The purified steam is then captured and cooled in a condenser, where it reverts back to its liquid state. This collected liquid is distilled water, which achieves its high level of purity through this phase change.
Chemical Composition and Purity Levels
The most significant difference between the two water types is reflected in their chemical makeup and purity levels. Tap water contains a measurable amount of Total Dissolved Solids (TDS), often ranging between 35 and 500 parts per million (ppm). These dissolved solids include beneficial, naturally occurring minerals such as calcium, magnesium, and potassium, which contribute to water hardness and flavor. Tap water may also contain trace amounts of substances added during treatment, like fluoride and residual chlorine compounds. While regulated to be safe for consumption, its content is a complex mixture of natural minerals and processing byproducts.
Distilled water is nearly 100% pure H₂O, possessing a TDS level close to zero, typically less than 10 ppm. The distillation process removes all dissolved solids, leaving a product that lacks both beneficial minerals and potential contaminants. Because it is stripped of these dissolved ions, distilled water is a poor conductor of electricity and is chemically neutral. This absence of dissolved solids causes distilled water to taste “flat” or bland. The lack of minerals also makes it slightly aggressive, as it attempts to dissolve carbon dioxide from the air and trace minerals from containers.
Everyday Uses and Consumption Safety
Tap water is the primary source for general household use, including drinking, cooking, and cleaning, due to its availability and mineral content. It is recommended for daily hydration because the trace minerals it contains, particularly calcium and magnesium, contribute to a person’s overall dietary intake. Municipal treatment ensures it is safe for consumption while retaining these desirable components.
Distilled water is reserved for applications where the absence of mineral buildup is paramount. It is used in equipment like steam irons, humidifiers, and CPAP machines, where mineral deposits could cause damage. Its purity also makes it the standard choice for laboratory experiments, medical sterilization, and automotive cooling systems.
While tap water is the standard for drinking, distilled water is safe to consume, though it is not ideal for long-term hydration. The lack of electrolytes means an individual’s diet must supply all necessary minerals to maintain proper balance. Drinking distilled water occasionally poses no risk, but relying exclusively on it can lead to a mild mineral deficiency if the diet is not balanced.