Ensuring drinking water quality is fundamental to public health. Many contaminants, like nitrates, are odorless, colorless, and tasteless, making them undetectable without specific testing. Understanding nitrates is important for maintaining water safety and protecting well-being.
Understanding Nitrates and Nitrites
Nitrates (NO₃) and nitrites (NO₂) are chemical compounds containing nitrogen and oxygen, naturally found in soil and water. Nitrates are generally more stable, but they can convert to nitrites through microbial action, particularly in the human digestive system. Nitrites are the more problematic form for human health.
Nitrates can enter drinking water from various sources. Agricultural runoff, containing fertilizers and animal waste from feedlots, is a common contributor. Leaking septic systems and industrial waste also introduce nitrates into groundwater. While low levels of nitrates occur naturally, elevated concentrations typically indicate human activity impacting the water supply.
Regulatory Standards for Drinking Water
Government agencies establish acceptable levels for contaminants in drinking water to safeguard public health. The U.S. Environmental Protection Agency (EPA) sets Maximum Contaminant Levels (MCLs) for public drinking water systems under the authority of the Safe Drinking Water Act (SDWA). These MCLs are enforceable standards that public water supplies must meet.
For nitrate, the EPA’s MCL is 10 milligrams per liter (mg/L), measured as nitrogen (10 ppm as N). The MCL for nitrite is 1 mg/L, also measured as nitrogen (1 ppm as N). These specific values are based on health research to prevent adverse effects. Federal standards apply to public water systems, but private wells are not federally regulated. Owners of private wells are responsible for testing and treating their own water. States may also have their own regulations, which can sometimes be stricter than federal guidelines.
Health Implications of High Nitrate Levels
Elevated nitrate concentrations can pose health risks, particularly for vulnerable populations. The most significant concern is methemoglobinemia, commonly known as “blue baby syndrome,” primarily affecting infants under six months of age. This condition occurs when nitrates, once ingested, are converted to nitrites in the infant’s digestive tract.
Nitrites then interfere with the blood’s ability to transport oxygen. They oxidize the iron in hemoglobin, the protein responsible for oxygen carriage, forming methemoglobin. Methemoglobin cannot effectively release oxygen to the body’s tissues, leading to a bluish discoloration of the skin and potentially shortness of breath. Infants are especially susceptible because their digestive systems are more prone to this conversion, and their fetal hemoglobin is more easily oxidized. Pregnant women and individuals with certain enzyme deficiencies may also face increased risks from high nitrate levels.
Testing Your Water for Nitrates
Determining nitrate levels in drinking water is a proactive step, especially for private well owners who are solely responsible for their water quality. Regular testing is recommended to ensure safety.
Certified laboratory testing offers the most accurate and reliable results. Homeowners can contact their local health department or state environmental agencies to find state-certified laboratories. These labs adhere to specific scientific methods approved by the EPA, ensuring the validity of test outcomes. While home testing kits are available, they are generally considered screening tools and are less accurate than laboratory tests. If a home test indicates the presence of nitrates, it is prudent to follow up with a certified laboratory for confirmation and precise measurement.
Reducing Nitrate Levels in Drinking Water
If water testing reveals elevated nitrate levels, several treatment methods can effectively reduce them. Reverse osmosis (RO) systems are widely recognized for their ability to remove nitrates. These systems work by forcing water through a semi-permeable membrane that filters out larger molecules, including nitrates, often removing 90% to 98% of them. RO units are typically point-of-use systems, treating water at a single tap.
Distillation is another effective method. Water is heated to create steam, leaving impurities like nitrates behind, and the condensed steam is collected as purified water. Ion exchange systems can also remove nitrates by exchanging nitrate ions for other harmless ions. These systems can be used for whole-house treatment. Beyond treatment, maintaining well systems properly can help prevent nitrate intrusion. Consulting water treatment professionals can help tailor solutions to specific water quality needs.