What are Nitrates/Nitrites and how are they used?
Nitrates and nitrites are nitrogen-oxygen chemical units which combines with
various organic and inorganic compounds. Once taken into the body, nitrates are
converted into nitrites. The greatest use of nitrates in the U.S. is as a fertilizer.
Why are Nitrates/Nitrites in water being regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law requires
to determine safe levels of chemicals in drinking water which do, or may cause
health problems. These non-enforceable levels, based solely on possible health
risks and exposure, are called Maximum Contaminant Level Goals.
The MCLG for nitrates has been set at 10 parts per million (ppm), and for
nitrites at 1 ppm, because the EPA believes this level of protection would not cause
any of the potential health problems described below.
Based on this MCLG, EPA has set an enforceable standard called a Maximum
Contaminant Level (MCL). MCLs are set as close to the MCLGs as possible,
considering the ability of public water systems to detect and remove
contaminants using suitable treatment technologies. Private well water is
solely the responsibility of the individual water well homeowner.
The MCL for nitrates has been set at 10 ppm, and for nitrites at 1 ppm,
because EPA believes, given present technology and resources, this is the lowest
level to which water systems can reasonably be required to remove this
contaminant should it occur in drinking water.
These drinking water standards and the regulations for ensuring these
standards are met, are called National Primary Drinking Water Regulations. All
public water supplies must abide by these regulations.
What are the health effects?
Short-term: Excessive levels of nitrate in drinking water have caused serious
illness and sometimes death. The serious illness in infants is due to the
conversion of nitrate to nitrite by the body, which can interfere with the
oxygen-carrying capacity of the child's blood. This can be an acute condition in
which health deteriorates rapidly over a period of days. Symptoms include
shortness of breath and blueness of the skin.
Long-term: Nitrates and nitrites have the potential to cause the following
effects from a lifetime exposure at levels above the MCL: dieresis, increased
starchy deposits and hemorrhaging of the spleen.
How much Nitrates/Nitrites are produced and released to the environment?
Most nitrogenous materials in natural waters tend to be converted to nitrate,
so all sources of combined nitrogen, particularly organic nitrogen and ammonia,
should be considered as potential nitrate sources. Primary sources of organic
nitrates include human sewage and livestock manure, especially from feedlots.
The primary inorganic nitrates which may contaminate drinking well water are
potassium nitrate and ammonium nitrate both of which are widely used as
According to the Toxics Release Inventory, releases to water and land totaled
over 112 million pounds from 1991 through 1993. The largest releases of
inorganic nitrates occurred in Georgia and California.
What happens to Nitrates/Nitrites when they are released to the environment?
Since they are very soluble and do not bind to soils, nitrates have a high
potential to migrate to ground water, and eventually into well water. Because they do not evaporate,
nitrates/nitrites are likely to remain in water until consumed by plants, other organisms
How will Nitrates/Nitrites be detected in and removed from my well drinking
The regulation for nitrates/nitrites became effective in 1992. Between 1993
and 1995, EPA required water suppliers to collect water samples at least
once a year and analyze tem to find out if nitrates/nitrites are present above
50 percent of their MCLs in drinking water. If it is present above this level, the
water system must
continue to monitor this contaminant every 3 months.
If water contaminant levels are found to be consistently above their MCLs, water suppliers must take steps to reduce the amount of nitrates/nitrites so that
they are consistently below that level. The following treatment methods have
been approved by EPA for removing nitrates/nitrites: Ion exchange,
Home Drinking Water Reverse
Osmosis Systems, Electrodialysis.
For removal of nitrates in drinking water the
preferred method that is highly effective is reverse osmosis
(RO). Reverse osmosis drinking water systems are very
reasonably priced and can be easily maintained by the
How will I know if Nitrates/Nitrites are in my well drinking water?
If the levels of nitrates/nitrites exceed their MCLs, the system must notify
the public via newspapers, radio, TV and other means. Additional actions, such
as providing alternative drinking water supplies, may be required to prevent
serious risks to public health.
Drinking Water Standards (ppm): MCLG MCL
Nitrate and Nitrite Releases to Water and Land: 1991 to 1993 (in pounds)
||Top Fifteen States*
|Misc. Ind. inorganics
|Misc. Metal ores
|Misc. Ind. organics
* State/Industry totals only include facilities with releases greater than