Nitrates are naturally occurring compounds composed of nitrogen and oxygen, found in air, soil, and water. While essential nutrients for plants and animals, their presence in well water can become a concern for human health. Unlike many other contaminants, nitrates are colorless, odorless, and tasteless, making them undetectable without specific testing. Monitoring nitrate levels in private well water is therefore an important step for well owners to ensure the safety of their drinking supply.
Health Effects of Nitrate Contamination
Elevated nitrate levels in drinking water pose a particular health risk to infants, leading to a serious condition known as methemoglobinemia, or “blue baby syndrome.” This occurs when ingested nitrates convert to nitrites in the body, especially in infants’ less acidic stomachs. These nitrites then interfere with the blood’s ability to transport oxygen by changing hemoglobin to methemoglobin. Infants under six months old are most susceptible because their digestive systems are still developing.
Symptoms of methemoglobinemia can include a bluish or brownish tint to the skin, particularly around the mouth and eyes, and breathing difficulties. Severe cases can rapidly progress and, if untreated, may lead to serious illness or even death. While less common, certain adults with specific health conditions, such as low stomach acidity, anemia, or some genetic disorders, may also be more vulnerable. Long-term exposure to nitrates has also been explored for potential links to thyroid problems, adverse pregnancy outcomes, and certain cancers, though further research is ongoing.
Understanding Acceptable Nitrate Levels
The U.S. Environmental Protection Agency (EPA) has established Maximum Contaminant Levels (MCLs) for nitrates and nitrites in drinking water to protect public health. The MCL for nitrate is 10 milligrams per liter (mg/L), measured as nitrogen (N). Similarly, the MCL for nitrite is 1 mg/L, also measured as nitrogen (N).
For private well owners, while the EPA does not directly regulate individual wells, these MCLs serve as a critical guideline for water quality. The standard is expressed as “nitrogen” (N) because it accounts for the nitrogen component of the nitrate or nitrite molecule. Adhering to these federal standards helps ensure the water is safe for consumption, particularly for vulnerable populations like infants.
How to Test Your Well for Nitrates
It is generally recommended that private well owners test their water for nitrates annually. This routine testing helps identify potential contamination early, as nitrate levels can fluctuate throughout the year due to various environmental factors.
For the most accurate results, samples should be sent to a state-certified laboratory. These laboratories use EPA-approved methods and provide comprehensive reports on contaminant levels. Local health departments, university extension offices, or state environmental agencies can often provide lists of certified labs and guidance on proper sample collection procedures.
While home test kits are available and offer a convenient initial screening, their accuracy and reliability are typically lower than certified lab tests. If a home test indicates the presence of nitrates, it is advisable to follow up with a certified laboratory analysis for precise confirmation.
Solutions for High Nitrate Levels
If well water testing reveals nitrate levels above the acceptable standard, immediate action is necessary. It is crucial to understand that boiling water does not remove nitrates; instead, it concentrates them as water evaporates, making the problem worse. Effective nitrate removal requires specific treatment technologies.
Common and effective methods for treating high nitrate levels include reverse osmosis (RO), ion exchange, and distillation systems. Reverse osmosis systems push water through a semi-permeable membrane that filters out most contaminants, including nitrates.
Ion exchange systems utilize a special resin that swaps nitrate ions for other ions, often chloride, as water passes through. Distillation involves heating water to produce steam, which then condenses into purified water, leaving nitrates and other impurities behind.
These treatment systems can be installed as point-of-use (POU) units at a single tap for drinking and cooking water, or as point-of-entry (POE) systems to treat all water entering the home. For infants and other vulnerable individuals, using an alternative safe water source, such as bottled water, is advisable until a treatment system is in place and confirmed to be effective.