The Dangers of Nitrates in Drinking Water

What are Nitrates?

Nitrates are chemical compounds composed of nitrogen and oxygen, commonly represented by the formula NO3-. They are naturally occurring and play an essential role in plant growth, making them a critical component of fertilizers. In addition to their presence in soil and water, nitrates also form as a byproduct of organic decomposition. While they are beneficial in agriculture, excessive amounts in drinking water can be harmful to human health, particularly for infants and pregnant women.

How Do Nitrates Get in Drinking Water?

Nitrates enter drinking water primarily through agricultural runoff, industrial waste, and septic system leakage. The use of nitrogen-based fertilizers is one of the leading causes of nitrate contamination, as rain and irrigation water wash nitrates from the soil into nearby streams, rivers, and groundwater supplies. Livestock operations also contribute significantly to nitrate pollution through manure runoff. Additionally, improperly constructed or failing septic systems can leach nitrates into groundwater, particularly in rural areas where many residents rely on private wells. Industrial activities, including wastewater discharge, can further contribute to nitrate presence in drinking water sources.

The Top 5 Ways Nitrates End Up in Drinking Water

1. Agricultural Runoff – The most significant source of nitrate contamination comes from nitrogen-based fertilizers used in farming. Rain and irrigation water wash excess nitrates from fields into rivers, lakes, and groundwater, leading to widespread contamination.
2. Livestock Waste and Manure – Animal waste, especially from concentrated animal feeding operations (CAFOs), contains high levels of nitrogen. If not properly managed, manure can seep into groundwater or be carried by runoff into drinking water sources.
3. Septic Systems and Wastewater Treatment Plants – Poorly maintained or aging septic systems can leach nitrates into groundwater. Additionally, some wastewater treatment plants do not fully remove nitrates before discharging treated water into rivers and streams.
4. Industrial and Urban Pollution – Certain industrial activities, such as food processing, chemical manufacturing, and fertilizer production, can release nitrates into nearby water bodies. Urban runoff, including lawn fertilizers and vehicle emissions, also contributes to nitrate pollution.
5. Natural Sources and Soil Decomposition – Nitrates naturally occur in the environment through the breakdown of organic matter and nitrogen cycle processes. In some cases, geological formations contain nitrogen-rich minerals that slowly leach nitrates into groundwater over time.

How Do Nitrates Affect Humans?

Excessive nitrate consumption poses several health risks, particularly for vulnerable populations such as infants and pregnant women. One of the most well-known health concerns is methemoglobinemia, also known as “blue baby syndrome,” a condition that reduces the blood’s ability to carry oxygen, leading to suffocation-like symptoms in infants. Long-term exposure to high nitrate levels has been linked to various health issues, including an increased risk of colorectal cancer, thyroid disease, and birth defects. Some studies suggest that nitrates may also contribute to cardiovascular diseases by interfering with the body’s ability to regulate blood pressure. Because nitrates convert into nitrites in the body, they can form carcinogenic compounds known as nitrosamines, which have been associated with different types of cancers.

What Parts of the USA Have the Most Nitrates?

Nitrate contamination is a widespread issue across the United States, with the highest concentrations found in agricultural regions. The Midwest, including Iowa, Nebraska, Kansas, and Illinois, experiences some of the most severe nitrate pollution due to intensive farming practices and fertilizer use. California’s Central Valley is another hotspot, as large-scale farming and dairy operations contribute significantly to groundwater contamination. Additionally, parts of Texas and Florida struggle with elevated nitrate levels, primarily due to agricultural runoff and poorly managed septic systems. In rural communities where residents rely on private wells, nitrate contamination is particularly concerning, as these water sources are not subject to the same level of government regulation as public water supplies.

What is the Government Doing About Nitrates?

The U.S. Environmental Protection Agency (EPA) regulates nitrate levels in public drinking water systems under the Safe Drinking Water Act, setting the maximum contaminant level (MCL) at 10 milligrams per liter (mg/L). To mitigate contamination, the government funds programs to help farmers implement best management practices, such as buffer strips, cover crops, and controlled fertilizer application. Some states, including Iowa and California, have established nitrate reduction initiatives and groundwater monitoring programs to track contamination levels. The USDA’s Conservation Reserve Program also encourages farmers to adopt conservation methods to reduce runoff and protect water sources. Despite these efforts, nitrate pollution remains a significant challenge, particularly in regions heavily dependent on agriculture.

Nitrate Contamination Events in the USA

One of the most notable nitrate contamination events occurred in Des Moines, Iowa, where the Des Moines Water Works filed a lawsuit in 2015 against upstream agricultural drainage districts for excessive nitrate pollution in the Raccoon River, a primary drinking water source. The lawsuit highlighted the challenges of controlling agricultural runoff and the burden on water treatment facilities to remove contaminants before distributing drinking water.

Another significant event took place in California’s Central Valley, where nitrate contamination has been an ongoing issue due to intensive farming and dairy operations. In 2012, the State Water Resources Control Board issued a report stating that over 250,000 residents in the Tulare Basin and Salinas Valley were at risk of consuming unsafe nitrate levels. The contamination has led to costly water treatment efforts and the need for alternative water sources in some communities.

In Wisconsin, a 2019 study found that private wells in Kewaunee County had alarmingly high nitrate levels due to a combination of manure spreading and improper septic system management. The findings raised concerns about the safety of drinking water in rural communities and prompted state officials to push for stricter regulations on manure application and improved groundwater monitoring.

How to Remove Nitrates from Your Drinking Water

Pitcher and Carbon Filters

Many households use pitcher filters or carbon-based filtration systems to improve drinking water quality. However, these types of filters are ineffective at removing nitrates. While they can eliminate certain contaminants, such as chlorine, lead, and volatile organic compounds (VOCs), they do not target nitrate molecules. As a result, individuals relying on carbon-based filters may still be exposed to unsafe nitrate levels if their water source is contaminated.

Reverse Osmosis (RO) Systems

Reverse osmosis (RO) can remove some nitrates from drinking water. RO systems use a semipermeable membrane to filter out contaminants, including nitrates, heavy metals, and other dissolved solids. These systems can remove up to 90% of nitrates. However, RO systems require regular maintenance, and they produce wastewater as a byproduct, which may be a drawback for some users.

Distillation

Distillation is highly effective method for nitrate removal. This process involves heating water until it turns into steam, then condensing it back into liquid form, leaving contaminants behind. Since nitrates do not evaporate with the water, they are effectively separated and left behind during distillation. Distillation systems provide nearly 100% nitrate removal.

Why You Should Care About Nitrates in Your Drinking Water

Nitrate contamination is a pressing public health issue, particularly for those living in agricultural regions or relying on private wells. Exposure to high nitrate levels can lead to severe health problems, including methemoglobinemia in infants and an increased risk of cancer and thyroid disorders. Government regulations and agricultural best practices aim to mitigate nitrate pollution, but many communities still struggle with unsafe drinking water. Understanding how nitrates enter water supplies, their potential health impacts, and the best filtration methods can help individuals make informed decisions about their water quality. Investing in effective water treatment solutions, such as distillation, is essential for those at risk of nitrate exposure. By taking proactive steps to monitor and purify drinking water, individuals can protect themselves and their families from the harmful effects of nitrate contamination.