What is deionized water and how is it made?
Deionized (DI) water, also known as demineralized water, is water that has had its dissolved mineral ions removed through a process called ion exchange. This process involves passing water through specialized resin beds that are electrically charged. These resins attract and bind to ions like calcium ($Ca^{2+}$), sodium ($Na^{+}$), and magnesium ($Mg^{2+}$), replacing them with hydrogen ($H^{+}$) and hydroxide ($OH^{-}$) ions, which then combine to form pure water ($H_{2}O$).
Unlike distillation, which involves boiling and condensing water to leave most impurities behind, deionization is specifically designed to remove charged particles, or ions, leaving behind uncharged substances. This process is highly effective at producing water with extremely low electrical conductivity, which is crucial for sensitive industrial and laboratory applications.
Why drinking DI water is not ideal for human health
While a single glass of deionized water is not likely to cause harm for a healthy person, it is not recommended for regular consumption, particularly over the long term. The primary reasons concern the lack of minerals and the incomplete purification process.
Lack of essential minerals
The deionization process removes beneficial mineral ions that our bodies utilize, such as calcium, magnesium, and potassium. While drinking water is not our primary source of these minerals, its consistent consumption contributes to our overall intake. Consistently drinking water without these minerals could put individuals at higher risk of deficiencies, especially if their diets are also lacking.
Potential for mineral leaching
Deionized water is often called "hungry water" due to its aggressive, demineralized nature. When consumed, it seeks to absorb minerals from its surroundings, including from the body's tissues. This could lead to a minor electrolyte imbalance and may leach minerals from your teeth, potentially increasing the risk of dental issues.
Corrosive properties and toxic leaching
Because DI water is highly purified and free of stabilizing minerals, it is aggressive and can leach metals and other substances from pipes and containers. If DI water is stored or transported through standard plumbing, it could pick up toxic metals like lead or plasticizers from PVC. This creates a risk of exposure to contaminants that were not originally in the water.
Pathogens remain present
A crucial point is that deionization is designed to remove ions, not neutral particles. This means uncharged organic compounds, viruses, and bacteria can remain in the water. Unless further purification steps like reverse osmosis or UV sterilization are used, deionized water is not microbiologically safe for drinking.
DI Water vs. Distilled Water: A Comparison
To highlight the key differences, here is a comparison of deionized and distilled water.
| Feature | Deionized (DI) Water | Distilled Water |
|---|---|---|
| Purification Process | Uses ion-exchange resins to remove mineral ions. | Water is boiled into steam, which is then condensed back into liquid. |
| Contaminants Removed | Removes charged mineral ions (e.g., salts, heavy metals). | Removes most minerals and biological contaminants like bacteria and viruses. |
| Contaminants Remaining | Uncharged contaminants, including many bacteria and viruses. | Some volatile organic compounds that may have a lower boiling point than water. |
| Purity Standard | Defined by very low electrical conductivity. | Defined by the removal of most impurities through vaporization. |
| Cost | Generally more cost-effective and faster to produce for large-scale industrial use. | More energy-intensive and costly to produce on a large scale. |
What are the practical applications of DI water?
Despite its unsuitability for regular drinking, deionized water is invaluable in many industries where mineral-free water is essential. Its key uses include:
- Laboratories: Used as a solvent for preparing chemical solutions, rinsing glassware, and for applications where ion interference must be avoided.
- Manufacturing: Essential in the production of electronics, cosmetics, and pharmaceuticals, where mineral deposits could damage equipment or contaminate products.
- Automotive: Used in car batteries and cooling systems to prevent mineral scale buildup and corrosion.
- Cleaning: Utilized for spot-free rinsing in car washes, window cleaning, and other surface cleaning applications.
- Aquariums: Can be used in fish tanks, after remineralization, to control the water chemistry for specific species.
Conclusion: Safe for industrial use, risky for drinking
Ultimately, while deionized water is not toxic and consuming a small amount is unlikely to cause immediate harm, it is not safe or recommended for regular hydration. The absence of essential minerals, its potential to leach minerals from the body and storage containers, and the presence of uncharged pathogens make it an unsuitable choice for drinking. A balanced diet provides most of our minerals, but regular, mineral-free water intake can disrupt our body’s balance over time. For safe, everyday drinking water, options like filtered tap water or remineralized reverse osmosis water are far better choices. For those interested in home water filtration, exploring options that balance contaminant removal with mineral retention is advisable.
Important Considerations for Water Purity
- Prioritize Health: For daily consumption, choose water that retains or adds beneficial minerals rather than removing all of them.
- Understand the Purpose: DI water has a purpose in specific industrial contexts, not for personal hydration.
- Beware of Leaching: Never store DI water in containers with potentially toxic materials that it could corrode and absorb.
Authoritative Source
For comprehensive information on water quality and the health impacts of different types of water, you can consult the World Health Organization (WHO). The WHO has published research and guidelines detailing potential health effects associated with consuming water with low mineral content.
Comparison Table
| Feature | Deionized Water | Distilled Water |
|---|---|---|
| Purification Method | Ion exchange resins. | Boiling and condensation. |
| Contaminants Removed | Mineral ions only. | Minerals and biological contaminants. |
| Microbiological Purity | Not guaranteed. | Generally microbiologically safer. |
| Taste | Often described as flat or unappealing. | Also flat, as minerals are removed. |
| Corrosive Nature | Can be highly corrosive and reactive. | Less corrosive than DI water due to process differences. |
| Ideal for Drinking? | No. | Safe in moderation if minerals are obtained elsewhere. |
| Cost | Generally cheaper for bulk industrial use. | More energy-intensive and expensive. |
Conclusion
Based on expert consensus, regularly drinking DI water is not safe or recommended due to the removal of essential minerals, potential for leaching, and risk of biological contaminants. DI water serves valuable industrial purposes but is fundamentally unsuitable as a primary source of hydration for humans. For drinking, opting for mineralized water or home-filtered water is a far safer and healthier choice.
Final Recommendations
- For Everyday Drinking: Stick to mineralized water sources.
- For Medical Advice: Consult a healthcare professional before altering your water source, especially for long-term use.
- For Industrial Needs: Ensure DI water is used for its specific, intended applications only.
- For Purity and Taste: Consider water filtration systems that balance contaminant removal with mineral retention.
Safety Precautions
- Never assume DI water is safe for drinking without verifying its specific purification process.
- Do not rely on DI water for long-term hydration, even in emergency situations.
- Always store DI water in inert containers to prevent leaching.
Summary
Regularly drinking deionized water poses risks due to mineral loss, corrosive properties, and unaddressed biological contaminants. It is safe for its intended industrial and laboratory applications but not for human consumption. Always opt for safer water sources for daily hydration.
Frequently Asked Questions
- What is the difference between DI water and distilled water? DI water removes ions using resins, while distilled water removes minerals and most biological contaminants by boiling and condensation. DI water does not remove uncharged pathogens.
- Can you get sick from drinking DI water? Yes, you can. Since deionization doesn't remove viruses or bacteria, if the source water was contaminated, drinking DI water could cause illness.
- Does DI water taste bad? Many people find the taste of deionized water to be flat or unappealing because the minerals that give water its taste have been removed.
- Will drinking DI water cause mineral deficiency? Prolonged or exclusive drinking of DI water can contribute to mineral deficiencies because it lacks essential minerals like calcium and magnesium that are beneficial to health.
- Is DI water more corrosive than tap water? Yes, DI water is more aggressive due to its high purity and can leach metals and substances from pipes and containers, potentially introducing toxic materials.
- Can you cook with deionized water? Using DI water for cooking is not recommended because it can pull minerals from the food, potentially reducing the nutritional value.
- What is a safer alternative to DI water for drinking? Filtered tap water, spring water, or remineralized reverse osmosis water are much safer alternatives for daily consumption.
