What are nitrates?
Nitrates (NO3) are an essential source of nitrogen (N) for plants. When nitrogen fertilizers are used to enrich soils, nitrates can be carried by rain, irrigation, and other surface waters through the soil to groundwater. Human and animal waste can also contribute to nitrate contamination of groundwater.
Although any well can become contaminated with nitrates, shallow, poorly constructed, or improperly located wells are more susceptible to contamination. Nitrate levels in drinking water can also be an indicator of overall water quality.
Elevated nitrate levels can suggest the possible presence of other contaminants, such as disease-causing organisms, pesticides, or other inorganic and organic compounds that could cause health problems.
Who is at risk from high nitrate levels in drinking water?
The Environmental Protection Agency (EPA) has set the Maximum Contaminant Level (MCL) for nitrate as nitrogen (NO3-N) at 10 mg / L (or 10 parts per million) for the safety of drinking water. Nitrate levels at or above this level are known to cause a life-threatening blood disorder in babies younger than six months of age called methemoglobinemia or “blue baby” syndrome; in which there is a reduction in the oxygen carrying capacity of the blood.
The symptoms of blue baby syndrome can be subtle and are often mistaken for other illnesses. A baby with mild to moderate blue baby syndrome may have diarrhea, vomiting, and / or be lethargic. In the most severe cases, babies will begin to show obvious symptoms of cyanosis: the skin, lips, or nail beds may develop a slate-gray or bluish color, and the baby may have trouble breathing. A sample of the baby's blood can easily confirm the diagnosis of blue baby syndrome.
Others at risk for excess nitrates in drinking water are:
- Pregnant women
- Individuals with reduced heartburn, and
- Individuals with an inherited lack of methemoglobin reductase.
Also, some health studies have suggested that exposure to high levels of nitrates could lead to some forms of cancer, but the results are not conclusive.
The only way to know if your drinking water is contaminated with nitrates is to have it tested. If you have a unique family (home) well, it is recommended that you test your water every three years for nitrates; more often if you live in an area with a history of high nitrate levels or if someone in your household is at risk for nitrate contamination.
What to do if you have high levels of nitrates in your drinking water:
If your drinking water sample was tested above the MCL for nitrates and you or someone else in your household is at risk of developing health problems due to high nitrate levels, it is recommended that you do not drink water. Find a safe, alternative water supply until you decide on a more permanent solution.
There is no simple way to remove all nitrates from your water. Finding and correcting the source of nitrate contamination is the best course of action. Although it is common to think of boiling, softening, or filtration as a means of purifying water, none of these methods reduce nitrate contamination. In fact, boiling water that contains high levels of nitrates can actually increase the concentration of nitrates.
Reverse osmosis, ion exchange, and distillation units could provide a home treatment to remove nitrates from water, but those processes can be complicated, expensive, and generally require routine maintenance. Activated carbon and other simple filters do not remove nitrates to any significant degree. Home treatment units are not generally recommended, especially as a permanent solution to ensure the use of nitrate-free water for children's use.
Your only long-term option may be to find a new water source. This can be accomplished by drilling a new well or connecting to a public water supply system that has acceptable levels of nitrate.
When selecting a new well (or looking for sources of nitrate contamination around the existing well), be sure to consider ALL possible sources of contamination. Unlike other pollutants, nitrates do not dilute and leach as water travels through the soil, so water wells:
- It must be separated from potential sources of nitrate contamination, including leaching and surface drainage, such as run-off from the pen.
- You should never be within 100 feet of a septic system, where there could be an opportunity for waste to enter the well.
- It must have a sanitary seal specifically designed for the top of the well casing. This seal must be correctly positioned, with all openings properly sealed, to prevent the entry of any possible contaminant into the well casing and eventually into the water source.
Also, inspect the surrounding areas within a 30 meter radius of the well for sources of contamination such as garbage, animal pens, barns, and especially agricultural areas where nitrogen fertilizers can contaminate groundwater (this includes your garden's House).
Original article (in English)