Nitrate (nitrate nitrogen) in drinking water
Delve into the essence of Nitrate Nitrogen, a compound present in our drinking water supply, commonly denoted by the symbol NO3-. This compound represents the nitrogen contained within the nitrate ion, distinguished from other nitrogen forms like ammonia or nitrite nitrogen. Concentrations are usually quantified in milligrams per liter of nitrogen. Nitrate nitrogen is frequently found in groundwater, with concentrations ranging from 0.1 mg/l to 3 or 4 mg/l in most areas, though certain locations may register levels up to 100 mg/l. It is often more abundant in shallow groundwater, frequently resulting from seeping through soil rich in nitrates or the application of certain fertilizers. Additionally, nitrates are a product of decomposing animal and human waste, hinting that their detection in water sources may signify contamination.
Recently, nitrate nitrogen has garnered attention due to its link with "blue babies." Infants younger than six months are susceptible to illness or even death at concentrations as low as 10 to 20 mg/l, which can impair the blood’s oxygen-carrying capacity and cause methemoglobinemia, or "blue baby" syndrome. This condition occurs when nitrates convert to nitrites in the alkaline environment of an infant’s gastrointestinal tract, disrupting the blood’s oxygen transport.
As sewage decomposes, soil bacteria convert nitrogen into nitrates, which plants absorb. However, due to nitrates’ high solubility, they can easily seep into groundwater during heavy rainfall or excessive irrigation. The presence of nitrate-nitrogen often suggests pollution from septic systems, cesspools, or similar sources. A substantial increase in nitrate-nitrogen levels in groundwater, which naturally contains low levels of nitrates, likely indicates contamination. Therefore, local or state health departments should regularly inspect well waters containing nitrate nitrogen.
What are the EPA’s guidelines regarding nitrate in drinking water? Post the 1974 Safe Drinking Water Act, the EPA set a maximum contaminant level for nitrate at 1 mg/L or 1 ppm. Some states may enforce stricter regulations. Community water systems must provide an annual water quality report to customers. However, there are still uncertainties about the health effects of nitrates in drinking water, including the amount ingested and the duration of exposure. It’s crucial to remain informed about your water’s nitrate levels and to consult with your water utility, particularly for private well users who are responsible for organizing and funding their water testing, as private wells are unregulated.
Preventing nitrate nitrogen contamination from human or animal waste is the best course of action. Wells should be located and constructed strategically to prevent sewage contamination. While processes like distillation, deionization, or reverse osmosis can remove nitrates, non-ionic nitrogen forms might not be filtered out. In commercial and industrial contexts, nitrates generally do not cause severe problems.
Since nitrate in water is colorless, odorless, and tasteless, regular testing is necessary to detect contaminants. Access to pure drinking water is a fundamental right, not a luxury, yet pollution challenges this access daily. Filtration systems, including reverse osmosis, are advised to protect health and purify water sources, whether from wells or municipal supplies. Considering the presence of outdated pipes in water distribution, filtration has become a prudent choice for every household, ensuring clean and healthy water for families and future generations.