Defining 'Pure': The Crucial Difference Between Purest and Healthiest
When people ask, "What is the purest water to drink?", they are often seeking the water with the fewest contaminants. The answer is technically distilled water, as it is chemically the most neutral and free of total dissolved solids (TDS). However, as the World Health Organization (WHO) has reported, the purest water isn't necessarily the healthiest for long-term consumption. The aggressive purification process that removes contaminants also strips away beneficial minerals like calcium and magnesium, which are vital for bodily function. Drinking demineralized water can cause the body to leach these minerals from its own tissues and food, leading to potential health issues. Therefore, the quest for the 'best' drinking water becomes a balance between removing harmful substances and retaining essential nutrients.
The Contenders for Purest Water
Distilled Water: The Chemical Benchmark
Distilled water is created by boiling water into a vapor, leaving behind impurities and minerals. The steam is then collected and condensed back into a liquid state. This process makes distilled water 99.8% pure, free of salts, minerals, heavy metals, and many chemical contaminants. Its neutral pH can, however, shift slightly to become more acidic as it absorbs carbon dioxide from the air.
Pros and Cons of Distilled Water
- Pros: Highly effective at removing contaminants, ideal for medical applications, lab work, and appliances where mineral buildup is undesirable.
- Cons: Lack of beneficial minerals, flat taste, corrosive nature that can leach materials from containers and plumbing, not recommended for long-term, exclusive consumption.
Reverse Osmosis (RO) Water: A Popular Compromise
Reverse osmosis forces water through a semi-permeable membrane at high pressure, effectively trapping a high percentage of impurities, including bacteria, viruses, dissolved salts, and heavy metals. Like distilled water, standard RO leaves water with very low mineral content. However, a key difference is that many modern RO systems include a remineralization stage to add back healthy minerals for better taste and improved health benefits.
Deionized (DI) Water: Not for Drinking
Deionization uses an ion exchange process to remove mineral ions from water, resulting in water with extremely low conductivity. However, this method does not remove uncharged molecules, including bacteria and viruses. DI water is primarily used in industrial and laboratory settings for its high chemical purity and should not be used as a regular source of drinking water.
Filtered Tap Water: Everyday Protection
Basic home water filters, such as activated carbon pitchers or faucet-mounted filters, remove common impurities like chlorine, which affects taste and odor. While not as pure as distilled or RO water, they are a practical and affordable option that leaves beneficial minerals intact.
Comparison of Common Drinking Water Types
| Feature | Distilled Water | Reverse Osmosis (RO) Water | Filtered Tap Water | Spring Water |
|---|---|---|---|---|
| Purity Level | Extremely high, near 100% H2O | High (removes up to 99% of contaminants) | Moderate (removes specific contaminants) | Varies (naturally filtered) |
| Mineral Content | Virtually none (demineralized) | Low (demineralized, but can be remineralized) | Varies (retains natural minerals) | High (naturally rich in minerals) |
| Taste | Flat and bland due to lack of minerals | Can be bland, but remineralization improves it | Good, with chlorine taste and odor removed | Often preferred, influenced by mineral profile |
| Common Use | Medical, laboratory, appliances | Drinking, cooking | Everyday drinking | Drinking, bottled water |
| Long-Term Health | Not recommended due to mineral leaching | Safe, especially with remineralization | Generally safe, depends on tap water quality | Generally safe |
| Cost | High energy cost for home production | Higher initial and maintenance cost | Low initial and maintenance cost | Varies, can be more expensive than tap |
The Health Debate: Purity Versus Mineral Content
For years, the debate over demineralized water has been ongoing. The WHO's extensive research highlights the potential risks of consuming water with insufficient mineral content, which is a major drawback for distilled and standard RO water. Minerals are more readily absorbed from water than from food, so drinking mineral-deficient water can exacerbate low dietary intake. Studies have linked low mineral intake from water to cardiovascular disease and weakened bones. For daily hydration, most experts favor drinking water that contains a healthy balance of minerals. This makes a home filtration system that retains minerals or an RO system with a remineralization filter a better long-term choice for many.
Which Water is Right for You?
Choosing the best water is a personal decision that depends on your health, budget, and local water quality. To make an informed choice, consider these steps:
- Assess Your Needs: If you need water for specific applications like CPAP machines or laboratory work, distilled water is the answer. For everyday drinking, look at alternatives.
- Test Your Tap Water: Get a local water quality report or test your home water to understand its content and identify any specific contaminants you might need to address.
- Explore Options: If your tap water is poor or you prefer enhanced taste, a comprehensive filtration system, or an RO system with remineralization, may be the best fit.
- Prioritize Minerals: For daily drinking, prioritize water that provides minerals. Bottled mineral or spring water is an option, as is filtered tap water, but environmentally and economically, a home system is often better.
Conclusion: Finding the Right Balance
Ultimately, while distilled water is technically the purest form of H2O, it is not the ideal choice for long-term daily consumption due to its lack of essential minerals. A better approach to achieving high-quality, healthy drinking water is through a method that effectively removes harmful contaminants while retaining or reintroducing beneficial minerals. Modern reverse osmosis systems with remineralization filters or quality whole-house and under-sink filters that leave minerals intact provide an excellent balance of purity and health benefits for daily hydration. Making a balanced, informed choice is key to ensuring the water you drink truly supports your well-being. For more information on the health impacts of demineralized water, consult the World Health Organization’s official reports, such as the one available here: WHO health risks from drinking demineralised water.
