Understanding the Purity of Purified Water
The fundamental principle behind purified water is removal, not addition. It is water from any source—such as tap water or groundwater—that has been treated to eliminate a wide array of contaminants. For water to be classified as 'purified', its total dissolved solids (TDS) count must not exceed 10 parts per million (ppm), a standard that ensures exceptionally high purity. This process is critical for producing water that is safe and clean, but it also has consequences for the water's final flavor and mineral content.
The Common Methods for Water Purification
Purified water can be produced using a combination of methods, with the most common being reverse osmosis, distillation, and deionization.
- Reverse Osmosis (RO): In this process, water is forced under pressure through a semi-permeable membrane. This membrane has tiny pores that allow water molecules to pass through while blocking dissolved salts, minerals, viruses, and bacteria. It is one of the most effective methods for removing a wide range of contaminants.
- Distillation: This method involves heating water to its boiling point and then collecting the condensed steam. Because most impurities have a higher boiling point than water, they are left behind. The result is very pure water, though it is a more energy-intensive process.
- Deionization: This chemical process uses ion-exchange resins to remove mineral ions from water. The resins exchange hydrogen and hydroxide ions for dissolved minerals, effectively producing highly pure water. However, this process does not effectively remove uncharged organic molecules, viruses, or bacteria.
The Importance of Remineralization for Flavor and Health
Because purification removes not only harmful contaminants but also beneficial minerals like calcium, magnesium, and potassium, the resulting water can often taste 'flat'. For this reason, many bottled water companies that sell purified water will add a select blend of minerals back into the water after purification, a process known as remineralization. These added ingredients, such as magnesium sulfate, potassium bicarbonate, or potassium chloride, are specifically chosen to improve the taste and add electrolytes. For at-home purification systems, mineral cartridges can be installed to add these beneficial minerals back in.
Purified vs. Spring Water: A Taste and Content Comparison
| Feature | Purified Water | Spring Water |
|---|---|---|
| Source | Can come from any source, including tap water or groundwater. | Must come from a protected underground source or aquifer. |
| Purification | Undergoes rigorous filtration (RO, distillation) to remove nearly all contaminants. | Minimally processed to remove harmful bacteria, but retains natural minerals. |
| TDS Level | Very low (ideally under 10 ppm), indicating high purity. | Can vary depending on the mineral content of the source, but generally higher than purified water. |
| Mineral Content | Almost all minerals are removed during purification, though some manufacturers add them back for taste and electrolytes. | Contains naturally occurring minerals like calcium, magnesium, and potassium, which contribute to its taste. |
| Flavor Profile | Generally neutral and clean-tasting, though can be 'flat' if minerals are not re-added. | Distinct flavor that varies based on its mineral content. |
The Controversy of Added Minerals
While adding minerals back to purified water is common practice for taste and nutritional enhancement, there are differing perspectives on its value. The World Health Organization has noted that, while pure water is vital, a complete lack of minerals might have some health implications. However, many health experts argue that the vast majority of our mineral intake comes from food, and the minerals in water are a negligible source. The decision to opt for purified water with or without added minerals often comes down to personal preference for taste and a consumer's dietary habits.
Conclusion: The Absence of Ingredients Is the Point
In the strictest sense, the "ingredients" in purified water are what have been removed. Through advanced processes like reverse osmosis and distillation, water is stripped of impurities such as bacteria, chemicals, and dissolved solids to create a product of exceptionally high purity. For many brands and at-home systems, the absence of natural minerals is countered by remineralization to improve flavor, a practice that highlights the subtle balance between safety and taste. Ultimately, understanding what makes water purified empowers consumers to choose the best option for their health and palate. For more on how purification affects water safety and standards, visit the U.S. Environmental Protection Agency's drinking water page.
Frequently Asked Questions
What makes purified water different from regular tap water?
Purified water undergoes advanced treatment to remove virtually all contaminants, including bacteria, chemicals, and dissolved solids, whereas tap water is only treated to meet minimum safety standards for public consumption.
Does purification remove beneficial minerals from water?
Yes, methods like reverse osmosis and distillation remove almost all dissolved solids, including beneficial minerals like calcium and magnesium. Some manufacturers add a blend of minerals back for taste.
Is purified water healthy to drink?
Yes, purified water is very healthy to drink, as it has had harmful contaminants removed. For long-term exclusive consumption, ensuring you get minerals from a balanced diet is wise, or choose a brand that adds minerals back in.
What does remineralization mean in purified water?
Remineralization is the process where bottled water companies add a select blend of minerals, such as magnesium sulfate or potassium chloride, back into purified water to improve its taste.
Is there a taste difference between purified and spring water?
Yes. Purified water generally has a clean, neutral taste, while spring water's taste is influenced by the naturally occurring minerals from its source.
Can I make purified water at home?
Yes, you can use home purification systems, such as reverse osmosis filters, or use simpler methods like boiling and distillation to purify water.
Does purified water contain electrolytes?
Originally, no, as the purification process removes them. However, many brands and some home systems add electrolytes back into the water after purification for flavor and potential health benefits.
What is Total Dissolved Solids (TDS)?
Total Dissolved Solids (TDS) is a measure of the amount of organic and inorganic materials, like metals, minerals, and salts, that have been dissolved in water. Purified water must have a very low TDS level.
