Distilled water, often perceived as the purest form of water due to its rigorous purification process, is not suitable for regular, long-term drinking. The distillation process involves boiling water and collecting the steam, which is then condensed back into liquid form. While this effectively removes contaminants, impurities, and most dissolved solids, it also strips the water of beneficial minerals and electrolytes essential for human health. The resulting demineralized water has a neutral pH, but upon contact with air, it absorbs carbon dioxide, becoming slightly acidic. This aggressive, mineral-depleted water is the primary reason it is ill-suited for daily hydration and can pose several health risks.
The Problem with Mineral Deficiency
One of the most significant drawbacks of drinking distilled water is the absence of key minerals like calcium, magnesium, and potassium, which are vital for numerous bodily functions. While a healthy diet should provide the majority of these nutrients, the water we drink contributes a supplementary amount that is easily absorbed by the body. Without these mineral contributions, particularly over the long term, mineral deficiencies can occur. For instance, low magnesium levels can lead to fatigue, muscle cramps, and headaches, while insufficient calcium can weaken bones and teeth. The mineral content of typical drinking water is especially beneficial for cardiovascular health and bone density.
The Electrolyte Imbalance and Dehydration Risk
Electrolytes are minerals that carry an electric charge when dissolved in water. They are crucial for nerve and muscle function, maintaining fluid balance, and regulating blood pressure. Distilled water, being devoid of these charged minerals, can disrupt the body's delicate electrolyte balance. When we sweat or urinate, we lose electrolytes along with water. Drinking water without electrolytes will not replenish this loss, potentially leading to an imbalance. This can paradoxically cause dehydration, as the body requires electrolytes to properly absorb and utilize water. In extreme cases, consuming large quantities of distilled water while fasting or after intense exercise can cause hyponatremia, a dangerously low level of sodium in the blood.
The 'Universal Solvent' Effect
As water passes through the ground, it naturally dissolves minerals from surrounding rocks and soil, earning it the nickname "the universal solvent". Because distilled water is aggressively pure, it lacks this natural mineral load and seeks to pull minerals from whatever it touches to achieve balance. This can mean leaching small amounts of minerals from the container it's stored in or, more importantly, from the body itself. The World Health Organization has noted that mineral-deficient water is more aggressive in leaching minerals from the body's tissues during digestion and can even pull calcium from bones and teeth over time. This effect also explains why using distilled water in appliances like irons or humidifiers prevents mineral buildup; the water simply reabsorbs those minerals.
Comparison of Water Types
| Feature | Distilled Water | Purified Water | Spring Water |
|---|---|---|---|
| Source | Boiled water condensed from steam | Tap or groundwater, purified by multiple methods (RO, distillation) | Naturally flowing from an underground source |
| Purification | Distillation (boiling and condensation) removes 99.9% of minerals and contaminants | Multiple processes remove contaminants, but some minerals may remain | Natural filtration through rocks and soil; bottled at the source |
| Mineral Content | Almost zero total dissolved solids (TDS), completely demineralized | Meets EPA standards, low TDS, may contain some minerals | Contains naturally occurring minerals like calcium and magnesium |
| Taste | Often described as flat, bland, or tasteless due to lack of minerals | Taste varies based on purification method and mineral content | Crisp and fresh, with a distinct taste from its natural mineral profile |
| Best for Drinking | Short-term use, especially with a balanced diet | Excellent for daily consumption | Excellent for daily consumption; often preferred for taste |
| Ideal for Appliances | Yes, prevents mineral buildup | Depends on the specific purification method; reverse osmosis is also effective | No, mineral content can cause buildup over time |
The Proper Uses for Distilled Water
Despite being unsuitable for long-term daily consumption, distilled water has many important applications where its lack of minerals is a necessity. Its purity makes it the gold standard in various fields:
- Medical Laboratories: Essential for preparing reagents, cleaning delicate instruments, and running diagnostic tests where contaminants could skew results.
- Sterilization: Used in autoclaves and other sterilization equipment to prevent mineral scale buildup and ensure effective cleaning of surgical tools.
- CPAP Machines: Recommended for use in continuous positive airway pressure (CPAP) machines to prevent mineral residue from accumulating in the humidifier.
- Automotive and Appliances: Used in car batteries, cooling systems, and steam irons to avoid corrosion and hard water stains.
- Aquariums: Some aquarists use distilled water to have full control over the mineral content for specific aquatic life.
Conclusion
Ultimately, while distilled water is remarkably pure and serves critical functions in medical and industrial settings, it is not the ideal choice for everyday human hydration. The removal of essential minerals and electrolytes makes it less effective for proper hydration and, over time, can contribute to significant health issues like mineral deficiencies and electrolyte imbalances. For daily drinking, mineral-rich alternatives such as spring water or properly filtered tap water are a far superior and healthier option. The best practice is to obtain most of your hydration from a variety of natural sources and a balanced diet. For more information on the adverse effects of consuming demineralized water, refer to reports from reputable organizations like the World Health Organization.
