The Dual Forms of Nitrogen in Your Bottle
Many consumers believe bottled water is simple, purified H₂O. However, the reality is more nuanced. Nitrogen can be found in bottled water in two primary forms: nitrogen gas (N₂) intentionally added during the bottling process and nitrogen-containing compounds like nitrates (NO₃⁻) and nitrites (NO₂⁻) that are naturally present from the water's source. Understanding this distinction is crucial to comprehending what's in your drinking water and why it's there.
Intentional Addition: Nitrogen Dosing for Shelf Life
For many still (non-carbonated) bottled beverages, manufacturers add a small drop of liquid nitrogen just before capping. This process, known as nitrogen dosing, serves multiple purposes:
- Pressurization and Rigidity: As the liquid nitrogen flashes to gas, it creates an overpressure within the bottle. This makes the lightweight plastic (PET) bottle more rigid, which protects it from damage during shipping and handling.
- Oxygen Displacement: Nitrogen is an inert gas, meaning it does not react with other elements like oxygen. By displacing the oxygen in the bottle's headspace, nitrogen creates a less reactive environment.
- Preventing Oxidation: Oxygen exposure can lead to oxidation, which causes deterioration in a product's taste, color, and overall quality over time. By minimizing oxygen, nitrogen dosing extends the shelf life and maintains the freshness of the water.
- Enhancing Carbonation: In carbonated beverages, nitrogen can be added to influence foam formation and mouthfeel.
Natural Presence: Nitrates and Nitrites
While nitrogen gas is added for packaging reasons, nitrates and nitrites are dissolved compounds that can be found in the source water itself. Nitrate is a nitrogen compound essential for plant growth, but at high concentrations, it can be harmful. The presence of nitrates in water can originate from several sources:
- Agricultural Runoff: Fertilizers used in farming are a major source of nitrogen compounds that can leach into groundwater and surface water.
- Septic Systems and Sewage: Improperly functioning or old septic systems can leak waste into the water supply, introducing nitrates.
- Animal Waste: Waste from confined animal feeding operations can contaminate groundwater with nitrates.
- Natural Decay: Decomposing organic matter from plants and animals can contribute to natural nitrate levels.
Regulatory Standards and Health Considerations
The presence of nitrates and nitrites in drinking water is regulated to protect public health. Regulatory bodies like the U.S. Environmental Protection Agency (EPA) and the U.S. Food and Drug Administration (FDA) set maximum allowable levels. The standard for nitrate (measured as nitrogen) is 10 mg/L.
High levels of nitrate are particularly concerning for infants under six months of age due to a condition called methemoglobinemia, or "blue baby syndrome". In infants, excess nitrates can interfere with the blood's ability to carry oxygen. For the general population, long-term exposure to elevated nitrate levels has been linked to potential health issues, including certain types of cancer and thyroid problems.
Comparison: Nitrogen Gas vs. Nitrate/Nitrite Nitrogen
| Feature | Intentional Nitrogen Gas (N₂) | Natural Nitrate/Nitrite Nitrogen (e.g., NO₃⁻) |
|---|---|---|
| Form | Inert gas added during bottling | Dissolved compounds from the water source |
| Purpose | Extends shelf life, adds bottle rigidity | No intended purpose; reflects source water quality |
| Source | Added by the manufacturer | Agricultural runoff, septic systems, natural decay |
| Health Impact | Non-reactive, safe for consumption | Regulated contaminant, dangerous for infants at high levels |
| Regulation | FDA considers it a processing aid | FDA and EPA regulate maximum contaminant levels |
How Different Water Types Compare
The level of natural nitrates in bottled water varies widely depending on its source. Bottled water can come from various sources, including natural mineral springs, protected groundwater aquifers, or treated municipal tap water.
- Spring/Groundwater: Water from these sources, particularly those in agricultural areas, may naturally contain trace amounts of nitrates due to leaching from soil and rock. Reputable bottled water brands test their water regularly to ensure compliance with federal standards.
- Purified/Municipal: Water sourced from a municipal supply and then purified (e.g., via reverse osmosis or distillation) has had most or all of its natural minerals and contaminants, including nitrates, removed during processing. The quality and purity are a result of the purification process, not the natural source.
For more detailed information on water quality standards, you can consult the official guidelines from the U.S. Environmental Protection Agency.
Conclusion
In summary, yes, there is nitrogen in bottled water, but it's important to distinguish between the two main types. The inert nitrogen gas is a safe and common additive used by bottlers to maintain product freshness and structural integrity. On the other hand, nitrate and nitrite nitrogen are naturally occurring compounds whose presence reflects the quality of the water source. Both are monitored and regulated by government agencies to ensure consumer safety. Most importantly, the levels of these compounds in commercially sold bottled water are well below the established safety standards, making them harmless to consume for most people. Always check the water source and any quality reports provided by the manufacturer if you have concerns about specific brands.
