Do they add anything to bottled water? The Truth About What's Inside

October 30, 2025 •

3 min read

According to the International Bottled Water Association, bottled water sales reached another all-time high in 2024, but many consumers remain unaware of what's inside. So, do they add anything to bottled water? The answer is frequently yes, especially to purified water, with minerals added for flavor and consistency.

Quick Summary

Bottled water brands often add minerals such as magnesium sulfate, potassium chloride, and sodium bicarbonate to purified water for a consistent taste profile. This process, known as remineralization, enhances the flavor that is lost during purification methods like reverse osmosis, distillation, or deionization. Natural spring and mineral waters have a different composition, originating with minerals already present from their underground sources.

Key Points

Purified Water Additives: Most purified bottled water, like Aquafina and Dasani, contains added minerals such as potassium chloride and magnesium sulfate to prevent a flat taste after the extensive purification process.
Flavor and Consistency: Minerals are added primarily to create a consistent and appealing taste profile that would otherwise be lost during purification methods like reverse osmosis.
Natural Mineral Water: Water labeled as 'natural mineral water' or 'spring water' is sourced from underground and naturally contains minerals, with federal regulations prohibiting added minerals.
Ozone Disinfection: Ozone is a common disinfecting agent used in bottling plants to ensure microbial safety, leaving trace amounts in the final product.
Regulatory Differences: Bottled water is regulated as a food product by the FDA, with federal quality standards required to be at least as stringent as the EPA's regulations for tap water.
Read the Label: The only way to know for sure what is in your bottled water, especially concerning added minerals or fluoride, is to check the ingredient list on the product's label.

Why Are Additives Necessary in Bottled Water?

For many bottled water brands, the process of purification strips the water down to a very 'flat' or neutral taste. While this removes contaminants, it also removes naturally occurring minerals that give water its distinct and refreshing flavor. To address this, many companies add specific minerals back into the purified water. This is a crucial step for market-leading brands like Dasani and Aquafina, who often start with municipal tap water. The practice ensures their product has a consistent, recognizable taste regardless of where it is bottled.

Common Additives and Their Purpose

Here's a breakdown of the typical minerals and compounds you might find on a bottled water label:

Magnesium Sulfate: Also known as Epsom salt, this compound is added as a flavor enhancer and contributes a slightly bitter taste.
Potassium Chloride: A mineral salt that can add a slightly bitter or salty flavor. It is also used as a potassium supplement and in salt substitutes.
Potassium Bicarbonate: Often used to regulate pH and alkalinity, it can also contribute to a smoother mouthfeel and flavor.
Sodium Bicarbonate: Also known as baking soda, this is another additive used for pH balance and taste enhancement.
Calcium Chloride: Used to add a slightly chalky or creamy flavor to mimic the profile of natural mineral water.
Ozone: Unlike the others, ozone is a gas used as a disinfectant during the bottling process to kill bacteria and viruses. Only trace amounts are left in the water, and its presence can sometimes be detected in the flavor.

The Difference Between Purified and Spring Water

The addition of minerals and flavor enhancers is most common in purified bottled water. Natural spring water, by definition, comes from a protected underground source and contains naturally occurring minerals. However, the specific mineral composition can vary depending on the geological region, which is why different spring water brands have unique tastes. Unlike purified water, federal regulations for mineral water prohibit the addition of minerals.

A Comparison of Bottled Water Types


Feature	Purified Bottled Water	Natural Spring Water	Naturally Mineral Water
Source	Municipal tap water or groundwater.	Protected underground source.	Geologically and physically protected underground source.
Mineral Content	Low to non-existent initially; minerals are added back for taste consistency.	Varies greatly depending on the spring's geology.	Must contain at least 250 ppm of Total Dissolved Solids naturally.
Taste Consistency	Highly consistent due to controlled reintroduction of minerals.	Varies from bottle to bottle due to natural fluctuations in the source.	Constant mineral content and relative proportions from the source.
Common Treatment	Reverse osmosis, distillation, and deionization.	Minimal processing, often just filtration.	Minimal treatment to maintain its original purity.
Additive Rules	Minerals and other compounds can be added.	No minerals can be added.	No minerals can be added.

The Regulation of Bottled Water

In the U.S., the Food and Drug Administration (FDA) is responsible for regulating bottled water as a packaged food product, not the Environmental Protection Agency (EPA), which oversees tap water. The FDA mandates that bottlers follow specific manufacturing practices and adhere to quality standards for over 90 different contaminants. For brands that add fluoride, the FDA also sets limits on the acceptable amount, whether naturally occurring or added. This oversight is critical to ensuring the safety of the product, although some independent studies have revealed varying quality levels in bottled water.

Conclusion

So, do they add anything to bottled water? The answer depends entirely on the type of bottled water you're buying. For purified water, additives like magnesium and potassium are essential for giving the water a consistent and palatable taste. For natural spring and mineral waters, the taste profile is determined by the inherent mineral content of its source. Reading the label is the most straightforward way to know exactly what's in your bottle, and it's clear that not all bottled water is simply 'just water.'

Frequently Asked Questions

The most common minerals added are magnesium sulfate, potassium chloride, potassium bicarbonate, and calcium chloride. They are used to enhance and balance the water's taste after purification.

Yes, adding minerals to bottled water is safe. The FDA regulates these additives, setting standards for the maximum levels of contaminants and ensuring the water is produced under sanitary conditions.

Many people prefer bottled water because of its consistent taste, which is achieved by adding a specific mineral mix. Distilled or heavily purified water can taste 'flat,' so the additives create a more pleasant flavor profile.

Not necessarily. The mineral content of bottled water varies by brand and type. Some hard tap water from groundwater sources can have a mineral content similar to or even higher than some bottled waters.

Some purified bottled water brands, particularly large market leaders, start with municipal tap water and then filter and add minerals. Other types, like spring water, are sourced differently.

Some bottled water brands add fluoride to promote dental health, similar to how many municipal water systems operate. If fluoride is added, it must be clearly labeled on the bottle.

The best way to know what's in your bottled water is to read the ingredient label. By law, bottled water with added ingredients must list them.