Understanding the difference: RO vs. DI Water
To understand whether it is okay to drink RO DI water, it is crucial to differentiate between these two purification methods. While both processes produce highly purified water, their mechanisms and end products are fundamentally different, with significant implications for drinking safety.
What is Reverse Osmosis (RO) Water?
Reverse osmosis forces water through a semi-permeable membrane that is designed to block nearly all contaminants, including dissolved salts, heavy metals like lead and arsenic, and harmful microorganisms such as bacteria and viruses. RO water is prized for its high level of purity, which improves taste and odor. However, the process is indiscriminate, meaning it also removes beneficial minerals like calcium, magnesium, and potassium that are naturally found in water. Modern RO systems often include a remineralization stage or a TDS (Total Dissolved Solids) controller to reintroduce these minerals, ensuring a healthier and better-tasting final product.
What is Deionized (DI) Water?
Deionized water is created through a process called ion exchange, where water passes through specialized resin beads that attract and remove positively and negatively charged ions, which are essentially mineral salts. The key distinction is that DI purification only removes ions. This means that uncharged contaminants, such as bacteria, viruses, and organic compounds, can remain in the water. Because of this, pure DI water is not considered safe for consumption unless it has undergone additional purification steps to remove these other pathogens.
The Health Risks of Drinking Demineralized Water
Long-term consumption of demineralized water, particularly DI water, poses several health risks that water experts and organizations like the World Health Organization (WHO) have documented.
- Mineral Depletion and Deficiency: Water is not the primary source of minerals, but it provides a bioavailable source of essential elements like calcium and magnesium that are easily absorbed by the body. Consistently drinking water completely devoid of these minerals can contribute to deficiencies over time, especially if a person's diet is already lacking. The WHO has linked long-term consumption of low-mineral water to an increased risk of cardiovascular disease, bone fractures, and neurodegenerative diseases.
- Leaching of Toxic Metals: Demineralized water is naturally aggressive and highly corrosive. This means it can leach metals like lead and copper from plumbing and storage containers, leading to potentially increased intake of toxic metals.
- Gastrointestinal and Metabolic Issues: The absence of minerals can disrupt the body's water and electrolyte metabolism, potentially leading to imbalances. Some individuals may experience digestive issues, including gastritis and acid reflux, from the slightly acidic pH of pure RO water.
- Unpleasant Taste and Poor Hydration: Demineralized water is often described as tasting 'flat' or 'off' due to the absence of minerals. This can make it less thirst-quenching, potentially leading to lower overall water consumption. While it still hydrates, it lacks the electrolytes needed to effectively replace what is lost during physical exertion, which can lead to fatigue or muscle cramps.
RO vs. DI Water for Consumption: A Comparison
| Feature | Reverse Osmosis (RO) Water | Deionized (DI) Water | Summary for Drinking |
|---|---|---|---|
| Purification Method | Uses a semi-permeable membrane to filter water. | Uses ion-exchange resins to remove charged ions. | RO is a comprehensive physical filtration method, while DI is a chemical process. |
| Removes Contaminants | Removes bacteria, viruses, heavy metals, and chemicals effectively. | Does not remove uncharged contaminants like bacteria and viruses. | RO water is biologically safer, while DI is not microbiologically secure. |
| Removes Minerals | Removes most dissolved minerals, requiring remineralization. | Removes all charged mineral ions, leaving water aggressive. | Both remove minerals, but DI water is exceptionally pure and corrosive. |
| Safety for Drinking | Safe for drinking, especially with remineralization or if consumed as part of a balanced diet. | Not recommended for drinking due to the risk of bacterial contamination and corrosiveness. | RO water is acceptable with precautions; DI water is not. |
| Taste | Often has a neutral or improved taste compared to tap water, especially with remineralization. | Described as 'flat' or 'insipid' because of the lack of minerals. | Remineralization can restore a pleasant taste to RO water. |
Making RO Water Safe for Long-Term Consumption
For those who choose to use an RO system, particularly in areas with poor water quality, making the water safe and healthy for long-term use is straightforward and involves mitigating the mineral loss. Here are several methods to remineralize your RO water:
- Install a Remineralization Filter: This is the most convenient option, as it is a cartridge added to the existing RO system. The filter reintroduces essential minerals like calcium and magnesium back into the water after purification, often balancing the pH as well.
- Use Mineral Drops: Concentrated trace mineral drops can be added to individual glasses or pitchers of RO water. This allows for manual control over the mineral content.
- Utilize Alkaline Water Pitchers: Some pitchers contain filters that add beneficial minerals to increase alkalinity. While effective for general filtration, they may not be sufficient for fully remineralizing RO water.
- Maintain a Balanced Diet: For individuals without dietary restrictions or specific health concerns, a diet rich in fruits, vegetables, and dairy can compensate for the mineral loss in drinking water.
Cautions for Children and Special Groups
It is especially important for growing children, pregnant women, and the elderly to ensure adequate mineral intake. Their higher nutritional needs mean that a reliance on non-remineralized RO water could potentially contribute to deficiencies that affect bone health and development. In these cases, using a remineralization filter or regularly adding mineral drops is highly advisable.
Conclusion
So, is it okay to drink RO DI water? The answer is a clear "no" for DI water, but a conditional "yes" for RO water. Deionized water is not safe for drinking because it does not remove biological contaminants and is corrosive. Conversely, RO water is a highly effective purification method that removes harmful substances. However, due to its removal of beneficial minerals, it is strongly recommended to use a remineralization filter or supplement your intake through diet, especially for long-term consumption. The key to safe, healthy water is understanding your purification method and taking the necessary steps to ensure a balanced mineral content. When it comes to your drinking water, purity should always be balanced with essential nutritional content. For more information, refer to guidelines published by the World Health Organization (WHO), which has detailed reports on the health risks of demineralized water.
Note: Always test your local water quality to determine the specific filtration needs for your home. Areas with high levels of contaminants may benefit most from RO systems, provided remineralization is also addressed.
What is the difference between RO and DI water?
| Feature | Reverse Osmosis (RO) | Deionized (DI) |
|---|---|---|
| Primary Function | A comprehensive filtration process that removes dissolved salts, chemicals, bacteria, and viruses through a semi-permeable membrane. | An ion exchange process that only removes mineral salts (ions). |
| Removes Harmful Pathogens? | Yes, effectively removes bacteria, viruses, and other microorganisms. | No, does not remove uncharged contaminants like bacteria and viruses. |
| Mineral Removal | Removes most beneficial minerals like calcium and magnesium. | Removes all charged mineral ions. |
| Taste | Neutral, often better than tap water; can be enhanced with remineralization. | Flat or insipid due to lack of minerals. |
| Safety for Drinking | Safe, especially with remineralization. | Not safe for drinking without further microbial treatment. |
When is RO Water Necessary?
An RO system is particularly beneficial when your tap water has high levels of contaminants that other filters cannot remove. This includes high Total Dissolved Solids (TDS), heavy metals like lead and arsenic, fluoride, and nitrates. In such cases, the benefits of removing harmful pollutants far outweigh the manageable drawback of mineral loss. However, if your tap water is already safe with low TDS, a simpler carbon filter may suffice.
How to Test and Remineralize Your Water at Home
To ensure your RO water is safe and healthy, it is wise to monitor its quality and remineralize it appropriately. You can purchase an affordable TDS meter to measure the total dissolved solids in your water, which gives you an indication of its mineral content. After using your RO system, you can add food-grade mineral drops or a pinch of unprocessed Himalayan salt, though mineral drops offer more precise dosing. For a set-and-forget solution, installing a remineralization cartridge on your RO system is the most convenient option.
