The Science Behind Purified Water and Minerals
Purified water is water that has been filtered or processed to remove impurities and contaminants like bacteria, viruses, and heavy metals. The extent to which minerals are removed depends heavily on the purification method used. Techniques like reverse osmosis (RO) and distillation are highly effective at stripping water of nearly all dissolved solids, including beneficial minerals like calcium and magnesium. Other methods, such as basic carbon filtration, are less aggressive toward mineral content.
Reverse Osmosis: The Mineral Stripper
Reverse osmosis is a popular and highly effective purification method that uses a semipermeable membrane. Water is forced through this membrane under pressure, and its tiny pores (around 0.0001 microns) allow water molecules to pass while blocking larger contaminants, including dissolved mineral ions. The result is a highly pure water, but one that is significantly lower in mineral content. The RO membrane is capable of removing 94-98% of minerals like calcium and magnesium. While this is excellent for eliminating harmful substances like lead and arsenic, it also removes the beneficial minerals that contribute to a person's daily intake.
Distillation: The Boiling Method
Distillation is a centuries-old purification process that involves boiling water to create steam, which is then condensed back into liquid form. This process is extremely effective at removing impurities and minerals because most solids and minerals do not vaporize at the same temperature as water. The resulting water is nearly 100% pure H2O, making it useful for industrial and medical purposes. The downside for drinking is that it has a very low or non-existent mineral content, which gives it a characteristically flat or bland taste. Like RO, distillation removes essential minerals from the water completely.
Other Filtration Methods
Not all water filters are designed for demineralization. Simpler and less aggressive filtration systems have varying effects on mineral content:
- Activated Carbon Filters: These filters use activated carbon to adsorb chemicals like chlorine and organic compounds that cause bad tastes and odors. They do not significantly remove beneficial dissolved minerals.
- Ultrafiltration (UF): This method uses a membrane with slightly larger pores (0.01-0.1 microns) than RO, allowing it to filter out bacteria, viruses, and suspended particles. It generally does not remove dissolved minerals and salts.
- Ion Exchange Filters: These systems replace undesirable mineral ions (like calcium and magnesium) with others (typically sodium) to produce soft water. While it removes the hardness minerals, it does not strip the water of all minerals and introduces sodium.
Health Implications of Mineral-Free Water
While purified water is a safer option if your tap water quality is questionable, exclusively drinking demineralized water over the long term can have potential health consequences. The minerals present in water, though a secondary source to a balanced diet, play a role in bodily functions. Long-term consumption of low-mineral water has been linked to potential electrolyte imbalances and other health issues, according to some reports.
Conversely, mineral-rich water is linked to several health benefits, including better heart health and bone density. This is why some manufacturers and health-conscious consumers choose to add minerals back into purified water to enhance its health benefits and taste.
Comparison of Water Types
| Feature | Distilled Water | Reverse Osmosis Water | Mineral-Enriched Purified Water |
|---|---|---|---|
| Mineral Content | Almost none (often <10 mg/L) | Very low (~95-99% removed) | Restored to healthy levels |
| Taste | Often described as bland or flat | Similar to distilled, can taste flat | Improved, more natural flavor |
| Purification Method | Boiling and condensation | Semi-permeable membrane pressure | RO/Distillation plus post-filtration or mineral addition |
| Typical Use | Medical equipment, laboratory, irons | Drinking, cooking, point-of-use systems | Daily drinking for health benefits |
| Key Benefit | Highest level of purity | Highly effective contaminant removal | Safe, pure, and mineralized water |
How to Ensure Healthy Mineral Intake
For those who prefer the purity of demineralized water but are concerned about their mineral intake, several strategies can be employed:
- Remineralization filters: Some RO systems and pitchers come with a final stage that adds beneficial minerals like calcium and magnesium back into the water after purification.
- Mineral drops: Add a few drops of concentrated trace minerals to a glass of purified water to restore its mineral content.
- Balanced diet: The most important source of essential minerals is a varied and healthy diet rich in fruits, vegetables, nuts, and meats.
- Mix water sources: Supplement demineralized water intake by occasionally drinking mineral water or naturally sourced spring water.
Conclusion
In conclusion, advanced purification methods like reverse osmosis and distillation do remove minerals, along with harmful contaminants, creating demineralized water. While this makes the water safer from pollutants, it can lead to a lack of beneficial minerals if relied upon exclusively over time. Consumers concerned about this can choose from a range of alternative filtration methods, remineralization solutions, or ensure a diet rich in essential minerals. Ultimately, understanding the process behind your water purification empowers you to make the healthiest choice for your specific needs. For more information on the health effects of demineralized water, see the review published by the National Institutes of Health.
