GWQ-00549
DRINKING
WATER
Nitrate in Drinking Water
Lisa Wedin and Fred Sorensen
This is the third in a series of publications on drinking water contaminants.
Nitrate is a nitrogen compound that is a potential
health hazard. It is highly soluble in water and can
seep into groundwater from septic tanks, animal
waste, fertilizers (manufactured and compost) and
sewage sludge. It is a serious health concern for
infants under six months of age.
Have the well tested regularly since nitrate and
many other contaminants cannot be seen, smelled
or tasted. The Environmental Protection Agency
(EPA) drinking water standard, or Maximum Contaminant Level (MCL), is 10 parts per million (ppm)
for nitrate. Nitrate can be removed from water by
distillation, reverse osmosis and ion exchange, or
bottled water can be used for drinking and cooking.
Types
The most common forms of nitrogen contaminants that are found in
groundwater are nitrate (NO3) and
nitrite (NO2).
EPA
The EPA regulates public water systems but not private water systems.
It is the individual’s responsibility to
test his or her well to make sure it
is free of contaminants. The EPA is
required to determine safe levels of
chemicals in drinking water. The EPA
MCL for nitrate (NO3-N) is 10 ppm
and for nitrite (NO2) it is 1 ppm.
Health considerations
Nitrate is a health concern for infants under six
months old, pregnant women and people with low
stomach acid. Infants under six months of age can
develop blue baby syndrome, or methemoglobinemia. Infants have bacteria in their stomach that
converts nitrate to nitrite. Nitrite enters the bloodstream. There it reacts with the hemoglobin to form
methemoglobin, which interferes with the blood’s
ability to carry oxygen. The infant may show signs
of suffocation.
Symptoms
The symptoms of methemoglobinemia are bluish
skin color, especially around the nose and mouth,
fussiness, tiredness, diarrhea or vomiting. The symptoms can be similar
Quick Facts about Nitrate
to a common cold. There is a simple
Type Natural compound that is
blood test for methemoglobinemia.
formed when nitrogen comOnce diagnosed, methemoglobines with oxygen
benemia is easily remedied. At six
Sources Fertilizers, septic sysmonths of age an infant develops
tems, animal waste, compost
enough stomach acid to kill the bacEPA MCL10 parts per million
teria that convert nitrate to nitrite.
(ppm)
In healthy adults and children,
nitrate is absorbed and excreted
rapidly. There are rarely any known
Indications Can’t smell, see or
effects for short-term exposure of a
taste it; must test for it
healthy adult or child to nitrate. It is
not known what the health effects
are of long-term consumption of nitrate.
Health Issues Causes blue baby
syndrome in infants
A Pacific Northwest Extension publication of the University of
Idaho, Oregon State University and. Washington State University in
cooperation with the University of Alaska Fairbanks
www.uaf.edu/ces or 1-877-520-5211
Livestock
Treatment options
Livestock health can also be affected by nitrate
contamination. Ruminants such as cattle and sheep
are more likely to suffer from nitrate poisoning.
High-nitrate water is considered a health hazard
when combined with high-nitrate feeds. In animals,
symptoms of methemoglobinemia include a lack of
coordination, labored breathing, blue membranes,
vomiting and abortions.
Do not boil the water. Boiling just concentrates the
nitrate. Nitrate is very soluble in water and difficult
to remove. Bottled water for cooking and drinking
is a good short-term strategy; long-term it would
be costly. There are three main treatment options
for removing nitrate: distillation, reverse osmosis
and ion exchange. Since nitrate is only harmful if
consumed, a point-of-use water treatment system
is adequate and more affordable than a wholehouse system.
Test
Test the well for nitrate. Generally, labs report
nitrate content in ppm of nitrate-nitrogen (NO3-N).
Some may report the results in ppm of NO3. Ten
ppm of NO3-N is equal 44 ppm of NO3. It is important to know in what units the results are reported
in order to determine whether the water if safe to
drink.
If the test comes in over 3 ppm, test the nitrate levels once or twice a year to make sure that they are
not increasing. If the well test results are above 10
ppm, install a water treatment system or switch to
another source of water for drinking and cooking.
Another option would be drilling a new well that is
either deeper or in a different location to tap into
water that is not contaminated by nitrate.
If the well is contaminated with nitrate, there could
also be microbial contamination. If the source of
contamination is a septic system, sewage line or
animal feces, the well could be contaminated by a
variety of microbial pathogens. Microbial testing
would be recommended.
Distillation
Distillation is an ancient form of water treatment
and is still in use today. It involves boiling the contaminated water. The nitrate does not evaporate
with the water. The steam is cooled and the purified
water condenses and is funneled into a separate
tank for use.
Reverse Osmosis
Reverse osmosis moves water from one side of a
membrane to the other, thereby purifying the water. The contaminants are left on one side and the
purer water gets collected for use.
Ion Exchange
Ion exchange purifies contaminated water by
trading nitrate molecules for chloride molecules
that are on special resin beads. One caution is that
if there are high amounts of sulfate present in the
water this process will not be as effective because
the sulfate competes with the nitrate in the ion
exchange process.
Nitrate Drinking Water Guidelines for Water with Known Concentrations of Nitrate
NO3-N
(ppm)
NO3
(ppm)
Drinking water guidelines
0 – 10
0 – 44
Safe for humans and livestock.
11 – 20
45 – 88
Generally safe for human adults and livestock. Do not use for human infants.
21 – 40
89 – 176
Short-term use for human adults acceptable. Short-term use for all livesotck is acceptable unless feed sources are high-nitrate. Long-term use poses risk. Do not use for human
infants.
41 – 100
177 – 440
Moderate-to-high risk for human adults. Moderate-to-high risk for young livestock. Acceptable for mature livestock if feed is low in nitrate. Do not use for human infants.
Over 100
Over 440
Do not use.
Table courtesy of University of Idaho Extension
Prevention
There are many ways to prevent possible contamination of the well. Wellhead protection can help
prevent wells from being contaminated with nitrate
or other contaminates. A properly constructed and
maintained wellhead will keep drinking water safe.
Potential sources of nitrate include septic systems,
animal waste and fertilizer. Properly maintain your
septic system: protect the drainfield and pump your
tank regularly. Keep animal waste away from your
wellhead. Follow the directions on the package
when using fertilizer, and don’t over fertilize.
There are situations that increase the likelihood of
nitrate contamination. Testing the well more frequently can prevent health problems from occuring
by letting the well users know whether they need
to treat their water or get an alternate source.
Nitrate Facts
In nature
1. Organic nitrates are present in human sewage and
animal manure.
2. Inorganic nitrates like potassium nitrate and ammonium nitrate are common fertilizers.
In water supplies
Potential Sources of Contamination
3. Public water systems are required to monitor their
water for nitrate. Private wells are not regulated.
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4. Test your well yearly for nitrate contamination.
Shallow well (less than 50 feet deep)
Feed lots
Agriculture
Golf courses and lawns
Septic systems (failing)
References
Center for Disease Control and Prevention. “Nitrate and Drinking Water from Private Wells.”
Last updated December 2009. www.cdc.gov/
healthywater/drinking/private/wells/disease/
nitrate.html
Mahler, R.L., Colter, A. and Hinryck, R. Nitrate and
Groundwater. 2007. University of Idaho Extension, Idaho Agricultural Experiment Station.
www.cals.uidaho.edu/edcomm/pdf/CIS/
CIS0872.pdf
U.S. Environmental Protection Agency. Consumer
Fact Sheet on NITRATES/NITRITES. www.epa.
gov/ogwdw/pdfs/factsheets/ioc/nitrates.pdf
Amounts
5. The EPA MCL for nitrate is 10 ppm or 44.3 ppm for
nitrate-nitrogen.
6. The EPA MCL for nitrite is 1 ppm.
Health
7. Nitrate is a serious health concern for infants under six
months of age, pregnant women and people with low
stomach acid.
8. It can cause blue baby syndrome (methemoglobinemia).
Treatment
9. Contaminated water can be treated by distillation,
reverse osmosis or ion exchange.
10.Bottled water can also be used for drinking and cooking.
Fred Sorensen, Extension Faculty, Natural Resources and Community Development, and Lisa Wedin, ResearchTechnician.
Published by the University of Alaska Fairbanks Cooperative Extension Service in cooperation with the United States Department
of Agriculture. The University of Alaska Fairbanks is an affirmative action/equal opportunity employer and educational institution.
©2014 University of Alaska Fairbanks.
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