Nitrate (nitrate nitrogen) in drinking water

Let’s get to know this Nitrate Nitrogen. The concentration of nitrates is commonly expressed as NO3-. The term "nitrate nitrogen" is used to refer to the nitrogen present which is combined in the nitrate ion. This nomenclature is used to differentiate nitrate-nitrogen from nitrogen in the form of ammonia (ammonia nitrogen), from nitrogen in the form of nitrite (nitrate-nitrogen), etc. The concentrations are usually expressed in milligrams per liter of nitrogen.

Many ground waters contain small amounts of nitrate nitrogen. Concentrations range from 0.1 mg/l to 3 or 4 mg/l in most areas. There are areas where amounts of nitrate can go as high as 100 mg/l have been found, however. Nitrates may occur in both shallow and deep well supplies, but they are most common in water from shallow wells. Nitrate nitrogen can result from the seepage of water through soil containing nitrate-bearing minerals. It may also occur as the result of using certain fertilizers in the soil; however, nitrates are one of the products of the decomposition of animal and human wastes. Thus, the presence of nitrates in a water supply indicates possible pollution of the water.


Nitrate nitrogen has been much publicized in recent years in relation to the problem of "blue babies." In concentrations as low as 10 to 20 mg/1 nitrate nitrogen has caused illness and even death among infants under six months of age. If such water is used for supplemental or for complete bottle feeding, it may affect the ability of the blood to carry oxygen. This oxygen starvation is called methemoglobinemia, or more commonly, the "blue baby" condition. This serious illness in infants is caused because nitrate is converted to nitrite in the higher pH conditions existing in the stomachs and intestinal tracts of infants under six months of age. Nitrite interferes with the oxygen-carrying capacity of a child's or baby animal's blood. This is an acute disease in that the symptoms can develop rapidly. In most cases, health deteriorates rapidly over a period of days. Symptoms include shortness of breath and blueness of the skin.

In the process of decomposition, raw sewage undergoes a chemical change. Bacteria in the soil convert various forms of nitrogen to nitrate. This is beneficial because plants absorb nitrogen in nitrate form. However, nitrate is highly soluble and easily moves with water throughout the soil. During excessive rainfall or over-irrigation, nitrate will drain below the plant’s root zone and eventually reach groundwater. When nitrate-nitrogen occurs, it is considered evidence of pollution either from septic tank fields, cesspools, golf courses, parks, gardens, or naturally occurring sources of nitrogen. Where groundwater is known to contain little or no nitrate-nitrogen naturally, the appearance of any significant increase is a probable indication of pollution. Because of these factors, well waters containing nitrate nitrogen should be checked periodically by local or state health authorities.

What are EPA’s drinking water regulations for nitrate?

In 1974, congress passed the Safe Drinking Water Act. This law requires the EPA to determine the level of contaminants in drinking water which cause no adverse health effects to likely occur. The regulations for nitrate are 1mg/L or 1 ppm. However, some states may set more stringent levels for nitrate other than the EPA. The EPA requires that all community water systems provide a water quality report for their customers each year. Uncertainty exists in the connection between the levels of nitrate in drinking water. The volume ingested, the duration of exposure and risks are not fully understood. It is strongly recommended to be aware of what is in your water and contact the water utility to learn about the nitrate level in your water. If users are on a private well they will have to pay a fee to have the water tested because private wells are not currently regulated.

The best method for treatment of large nitrate nitrogen concentrations due to human or animal wastes is prevention. Wells should be properly located and constructed in order to prevent sewage contamination. Nitrates can be removed through distillation, deionization, or reverse osmosis. Even though about 95% of ionic nitrates can be removed by reverse osmosis, non-ionic forms of nitrogen are not rejected and pass through the membrane. In commercial and industrial water supplies nitrates do not usually present serious problems.

Nitrate in water is undetectable without testing because it is colorless, odorless, and tasteless. Thus, this makes it more important to always know the contaminants in your drinking water so you can plan your method of action. Having access to pure drinking water should not be a privilege; it should be available to all humankind. Nonetheless, pollution is making it harder every day to have access to pure water. Filtration systems are recommended to protect your health and to purify your drinking water source, whether it is well water or city water. Filtration systems such as reverse osmosis can remove contaminants, color, odor, heavy metals, bacteria and more. In our day and age filtration is recommended in every home because of the old pipes that are still used to transport our water. It is always best to take the precautions you need to provide clean and healthy water to your whole family and even future family members – the babies!

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