Nitrogen is a vital element for life, but its presence in drinking water is not as a simple, harmless gas. When people ask, "Does drinking water have nitrogen?" they are often concerned about its more reactive forms, such as nitrates ($NO_3^-$) and nitrites ($NO_2^-$). While atmospheric nitrogen gas ($N_2$) is harmlessly dissolved in all water, it is the contamination from nitrogen compounds that warrants attention and precaution. This guide breaks down the science behind nitrogen in your water, its sources, health implications, and what you can do to ensure your water is safe.
The Difference Between Nitrogen Gas and Nitrogen Compounds
Nitrogen exists in various forms, and understanding the difference is key to understanding water quality.
- Nitrogen Gas ($N_2$): The air is roughly 78% nitrogen gas, and it readily dissolves into water in small, harmless amounts. This is a natural part of aquatic ecosystems and is not a concern for human health. Water treatment processes do not need to remove it.
- Reactive Nitrogen Compounds: These are the problematic forms that get into water. Through the nitrogen cycle, nitrogen is converted into compounds like ammonia ($NH_3$), ammonium ($NH_4^+$), nitrite ($NO_2^-$), and nitrate ($NO_3^-$). Nitrates are the most common form found in contaminated drinking water, particularly from groundwater sources.
Why Are Nitrates a Concern?
Nitrates are highly water-soluble and can move easily through the soil and into groundwater, which is a primary drinking water source for many households, especially those on private wells. The U.S. Environmental Protection Agency (EPA) has set a Maximum Contaminant Level (MCL) for nitrate at 10 mg/L (or 10 parts per million, ppm) to protect public health. High levels of nitrates pose a serious, acute health risk, particularly to infants.
Sources of Nitrogen Contamination in Water
Nitrogen can enter a water supply from both natural and human-made sources. Human activities are often the cause of dangerously elevated levels.
- Agricultural Runoff: The most significant source of nitrogen contamination is from agricultural practices. Fertilizers and animal manure, which are rich in nitrates and other nitrogen compounds, can wash off fields and seep into groundwater and surface water during rain or irrigation.
- Wastewater and Septic Systems: Failing septic tanks and improperly managed wastewater systems can leak sewage into the ground. Human and animal waste contains nitrogen, which can lead to contamination of nearby water supplies.
- Atmospheric Deposition: Nitrogen-containing compounds from vehicle exhaust and industrial processes can enter the atmosphere. This reactive nitrogen eventually returns to earth in rain or snow and can make its way into water bodies.
- Natural Occurrences: While less common for high-level contamination, some natural processes can also contribute. Decomposing plant and animal matter can release nitrogen into the soil, which can then be transported to water. Natural geological formations can also contain nitrogen.
Health Implications of High Nitrate Levels
While adults can often consume moderate levels of nitrates without ill effect, certain groups, especially infants, are at high risk.
- Blue Baby Syndrome (Methemoglobinemia): This is the most serious and acute health risk associated with high nitrate intake in infants under six months old. In an infant's digestive system, nitrates can be converted to nitrites. These nitrites interfere with the blood's ability to carry oxygen, causing the baby's skin and lips to take on a bluish color. This is a medical emergency that can be fatal if left untreated.
- Potential Cancer Risk: Some studies have suggested a link between long-term exposure to high nitrate levels in drinking water and increased risk of certain cancers, like colorectal cancer, possibly through the formation of carcinogenic nitrosamines in the digestive system.
- Other Potential Effects: Research also continues to explore possible links between nitrates and other health issues, including thyroid problems and adverse pregnancy outcomes, though these connections require more confirmation.
What to Do if You Suspect Contamination
Comparison of Nitrogen Gas vs. Nitrates in Water
| Feature | Nitrogen Gas ($N_2$) | Nitrates ($NO_3^-$) |
|---|---|---|
| Source | Naturally dissolved from the atmosphere. | Human activities (fertilizer, waste) and natural decay. |
| Toxicity | Not toxic to humans or aquatic life. | Toxic in high concentrations, especially to infants. |
| Treatment Needs | No treatment needed for drinking water safety. | Must be removed if levels exceed EPA standards. |
| Detectability | No noticeable color, odor, or taste. | No noticeable color, odor, or taste. |
| Environmental Impact | Harmless. | Can cause harmful algal blooms (eutrophication). |
Action Steps for Water Safety
- Test your water: The only way to know if your water contains harmful levels of nitrates is to have it tested by a certified laboratory. If you use a private well, regular testing is crucial. Public water systems are required to test regularly and report findings to customers.
- Avoid boiling contaminated water: Boiling water actually increases the concentration of nitrates because the water evaporates while the nitrates remain. This is particularly dangerous for preparing infant formula.
- Consider alternative water sources: If tests show high nitrate levels, use bottled water for drinking and cooking, especially for infants.
- Install a treatment system: For long-term solutions, point-of-use or whole-house treatment systems can effectively remove nitrates. Common methods include reverse osmosis, ion exchange, and distillation. Regular maintenance of these systems is essential to ensure they remain effective.
- Identify and remove the source: Work with local health officials to investigate the source of contamination. Addressing the root cause, such as a failing septic system or fertilizer management practices, is a long-term solution.
Conclusion
While elemental nitrogen is a natural and harmless component of water, the presence of its compounds, primarily nitrates, poses a significant health concern, particularly for infants. Understanding the sources of contamination—from agricultural runoff to failing septic systems—is the first step toward mitigation. Regular testing, proper water treatment, and reducing pollution are all critical measures to protect the health of your family and ensure the safety of your drinking water. For more information on national drinking water standards, consult authoritative sources like the U.S. Environmental Protection Agency (EPA).
The Role of the Nitrogen Cycle
The movement of nitrogen through the atmosphere, soil, water, and living organisms is known as the nitrogen cycle. Human activities have significantly altered this natural process, leading to an excess of reactive nitrogen in the environment. Nitrogen-fixing bacteria naturally convert inert atmospheric nitrogen into a usable form for plants. However, the widespread use of synthetic fertilizers adds more nitrogen to the cycle than ecosystems can handle, causing the excess to leach into groundwater. This disruption is a major reason for the increased levels of nitrates found in drinking water today.
Preventing Contamination in Your Community
Combating nitrogen contamination requires community-wide efforts. Implementing better agricultural practices, such as precision farming to optimize fertilizer application, can reduce runoff. Proper maintenance of septic systems and wastewater treatment plants is also vital. Furthermore, protecting and restoring natural buffer zones, like wetlands, can help filter excess nutrients before they reach water bodies. Educating both farmers and homeowners about the importance of reducing nitrogen pollution is a powerful tool in protecting the public water supply. The EPA provides extensive resources on nutrient pollution and its sources, offering a roadmap for communities to improve water quality and protect against contamination.
