While reverse osmosis (RO) systems are highly effective at purifying water by removing most dissolved solids, drinking exclusively un-remineralized RO water can pose concerns due to its lack of essential minerals and its inability to remove certain contaminants.
The Core Concerns with Drinking Pure RO Water
Reverse osmosis works by forcing water through a semi-permeable membrane, which filters out salts, minerals, and other impurities. However, this process has specific implications for consumption:
- Mineral Depletion: RO water is stripped of beneficial minerals like calcium, magnesium, and potassium, which are vital for human health. Prolonged consumption of demineralized water, without reintroducing these minerals through diet or water re-mineralization, can contribute to mineral deficiencies. This lack of minerals also gives RO water a "flat" or unappealing taste to many.
- Persistent Contaminants: While incredibly effective at removing many impurities, reverse osmosis systems are not foolproof against all contaminants. For instance, dissolved gases, such as hydrogen sulfide, a common nuisance contaminant known for its characteristic rotten egg odor, can pass through the RO membrane. Additionally, some pesticides, solvents, and volatile organic chemicals (VOCs) are not consistently removed by RO systems. This means that while the water might be free of many typical pollutants, specific harmful chemicals or unpleasant gases could still be present.
- Slightly Acidic pH: Highly purified water tends to be slightly acidic, as the buffering capacity provided by minerals is removed. While the human body has mechanisms to regulate pH, consistently consuming acidic water without a balanced diet could be a minor concern for some individuals over long periods.
Understanding What RO Removes and Doesn't Remove
To illustrate, consider the effectiveness and limitations of RO technology:
| Category | What RO Effectively Removes | What RO May Not Fully Remove |
|---|---|---|
| Minerals & Salts | Calcium, Magnesium, Sodium, Potassium, Chloride, Fluoride, Nitrates | - |
| Heavy Metals | Lead, Arsenic, Chromium, Copper | - |
| Microorganisms | Bacteria, Viruses, Cysts | - |
| Particulates | Sediment, Rust, Dirt | - |
| Certain Chemicals | Chlorine, Chloramines (often with pre-filters) | Dissolved gases (e.g., hydrogen sulfide), some pesticides, solvents, volatile organic chemicals (VOCs) |
Addressing the Challenges of RO Water
Despite these concerns, reverse osmosis remains one of the most effective water purification methods available. Its output water can be made suitable for drinking with simple solutions:
- Remineralization: This is the most common and recommended solution. Many RO systems now include a post-filter that adds beneficial minerals back into the water after purification. This not only makes the water healthier but also significantly improves its taste.
- Balanced Diet: For those who consume RO water without re-mineralization, it is crucial to ensure that essential minerals are obtained through a balanced diet rich in fruits, vegetables, and whole grains.
- Blending: Some individuals choose to blend RO water with small amounts of mineralized tap water or bottled mineral water to achieve a desirable mineral content and taste.
- Contextual Use: RO water is excellent for specific applications where mineral-free water is beneficial, such as in humidifiers, irons, aquariums, or for certain types of cooking.
In conclusion, while RO water is exceptionally pure, its lack of minerals and potential for certain unremoved contaminants mean it's often best consumed after re-mineralization or as part of a varied hydration strategy.
