What Percentage of Bottled Water is Water?

December 21, 2025 •

3 min read

An estimated 25% or more of bottled water is actually just repackaged tap water, sometimes treated further and sometimes not. This reveals that the seemingly simple question, 'what percentage of bottled water is water?', uncovers a complex industry far from pure H2O.

Quick Summary

Bottled water contains dissolved solids and minerals, with a significant portion sourced from municipal taps. Purity levels, treatment methods, and health standards for bottled water vary and often differ from public tap water regulations.

Key Points

Sourcing Surprise: A significant portion (25% or more) of bottled water comes from municipal tap water sources.
Added Minerals: Bottled water isn't pure $H_2O$; it contains dissolved solids and minerals, sometimes added after purification to enhance taste.
Regulation Discrepancy: Public tap water, regulated by the EPA, is often subject to more rigorous monitoring and public reporting than FDA-regulated bottled water.
Plastic Concerns: Plastic bottles can leach harmful chemicals like BPA and microplastics into the water, with health implications, especially when bottles are reused or exposed to heat.
High Environmental Cost: The convenience of bottled water comes with a high environmental price due to petroleum-based plastic production, transport emissions, and plastic waste.
Taste vs. Purity: The unique taste of different bottled water brands comes from their specific mineral content, which can be natural or artificially added.
Cost Inefficiency: Bottled water is substantially more expensive than tap water, with the markup reflecting packaging and marketing, not necessarily superior quality.

The Surprising Truth: It's More Than Just H2O

While the main component of any bottle labeled as water is indeed dihydrogen monoxide ($H_2O$), it is rarely pure. The term 'bottled water' is an umbrella category covering several types of water, each with a different source and composition. The final product contains small, but impactful, percentages of other compounds, from naturally occurring minerals to added flavors and disinfectants. For example, brands selling 'purified water' often start with municipal tap water, treat it with processes like reverse osmosis, and then add minerals back for taste. This makes the final product more palatable, as pure water can taste 'flat'. Natural mineral water, on the other hand, gets its specific mineral profile directly from its underground source.

Understanding the Different Types of Bottled Water

Purified Water

Often sourced from municipal supplies (tap water).
Treated extensively using reverse osmosis, distillation, or deionization to remove dissolved solids and contaminants.
Minerals are often added back in to enhance flavor.

Spring Water

Collected from a natural underground source where water flows to the surface.
Contains naturally occurring minerals absorbed during its journey through rock and sediment.
Must have the same composition as the surface spring if collected via a drilled hole.

Mineral Water

Similar to spring water but must contain at least 250 parts per million of total dissolved solids (TDS).
The dissolved solids, such as calcium, magnesium, and potassium, must be present at the source.
Its mineral content gives it a distinctive taste.

Artesian Water

Drawn from an artesian well, which taps into a confined aquifer.
The natural pressure forces the water upward, often requiring little pumping.

How the Purity of Bottled Water Stacks Up to Tap

Consumers often assume bottled water is safer, but regulations differ significantly. Tap water, regulated by the Environmental Protection Agency (EPA), is subject to more stringent monitoring and reporting requirements than bottled water, regulated by the Food and Drug Administration (FDA).

Here is a comparison of bottled and filtered tap water:


Feature	Bottled Water	Filtered Tap Water
Regulation	Regulated by the FDA, often less stringently monitored with less public reporting.	Regulated by the EPA with strict, consistent monitoring, testing, and public reporting.
Cost	Significantly more expensive; cost is often hundreds to thousands of times higher per gallon.	Substantially cheaper, with minimal cost beyond the filter itself.
Contaminants	Can contain microplastics, chemical leachates (BPA, antimony), and sometimes bacteria.	May contain contaminants like chlorine and heavy metals depending on local infrastructure. Can be largely removed with a quality filter.
Environmental Impact	High carbon footprint from production and transportation; plastic bottles are a major source of waste and pollution.	Minimal environmental impact, reducing plastic waste and transportation energy.
Taste	Varies by brand and mineral content; often enhanced with additives.	Varies by region; filters can improve taste and remove odors.

The Real-World Costs Beyond the Price Tag

The convenience of bottled water comes with a heavy price for both your wallet and the planet. Environmentally, the production and disposal of plastic water bottles is a major issue. Most bottled water is packaged in PET plastic bottles derived from crude oil, and many end up in landfills or polluting waterways, not recycled. Health-wise, plastic bottles can leach harmful chemicals like Bisphenol-A (BPA) and phthalates, especially when exposed to heat or stored for extended periods. Studies have linked these endocrine-disrupting chemicals to various health problems. Microplastic contamination in bottled water is also a growing concern.

Conclusion: Making an Informed Choice

While marketing often suggests bottled water is purer and healthier, the reality is more nuanced. Bottled water is a mixture of $H_2O$ and various other components, which differ depending on the source and processing method. When considering what to drink, it's essential to look beyond the branding and assess the actual composition and safety standards. For many, investing in a home water filtration system provides a more affordable, sustainable, and transparently regulated option. For more details on tap water safety and bottled water myths, consult the SimpleLab Tap Score blog for in-depth research and studies.

Frequently Asked Questions

Technically, no. Even 'purified' water has trace amounts of dissolved solids. Distilled water is the closest to pure H2O, but it is typically used for machinery, not for drinking, and often has minerals added back for flavor.

The taste of bottled water is primarily determined by its mineral content. Different sources and geological locations impart different mineral profiles, and some manufacturers add specific minerals like magnesium sulfate or potassium chloride to purified water for taste.

Most brands using municipal sources must label their product as 'purified water'. However, a significant percentage of this type of bottled water begins as treated tap water. Labeling isn't always fully transparent about the original source, so checking third-party reports or brand websites is sometimes necessary.

Yes, some concerns include potential exposure to microplastics and chemical leaching, such as BPA and phthalates, from the plastic bottle, particularly when exposed to heat. Additionally, in some cases, bottled water has been found to contain contaminants above health benchmarks.

Tap water, regulated by the EPA, is generally more strictly regulated and consistently monitored. Bottled water is regulated by the FDA, often with less stringent monitoring, testing, and public reporting requirements.

This depends on personal preference. Spring water contains naturally occurring minerals, while purified water has been treated to remove almost everything, sometimes having minerals added back. The safety and purity of tap water is often higher than many believe.

The production and transportation of plastic bottles contribute significantly to fossil fuel consumption and carbon emissions. Furthermore, a large percentage of plastic bottles end up in landfills or as litter, contributing to plastic pollution.