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Does the state regulate nitrate in drinking water?
Yes. State law requires public water systems to
sample for many contaminants, including nitrate, on a
regular basis. Our drinking water quality standard for
nitrate is 10 milligrams per liter (mg/L). Public water
systems with nitrate levels over 10 mg/L must notify
people who receive water from them. |
Q & A: Nitrate in Drinking Water
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Nitrate is a chemical found in most fertilizers, manure, and
liquid waste discharged from septic tanks. Natural bacteria in
soil can convert nitrogen into nitrate. Rain or irrigation water
can carry nitrate down through the soil into groundwater. Your
drinking water may contain nitrate if your well draws from this
groundwater.
Nitrate is an acute contaminant. That means one exposure
can affect a person's health.
How does nitrate affect health?
It reduces the ability of red blood cells to carry oxygen. In
most adults and children, these red blood cells rapidly return
to normal. However, in infants it can take much longer for the
blood cells to return to normal. Infants who drink water with
high levels of nitrate (or eat foods made with
nitrate-contaminated water) may develop a serious health
condition due to the lack of oxygen. This condition is called
methemoglobinemia or “blue baby syndrome.” Some scientists think
diarrhea makes this problem worse.
Low levels of nitrate in water will not have a long-lasting
effect on your baby. If your baby doesn’t have any of signs of
blue baby syndrome, you do not need to have a doctor test for
methemoglobinemia.
What are the signs of blue baby syndrome?
Moderate to serious blue baby syndrome may cause
brownish-blue skin tone due to lack of oxygen. This condition
may be hard to detect in infants with dark skin. For infants
with dark skin, look for a bluish color inside the nose and
mouth, on the lips, or fingernail and toenail beds.
Mild to moderate blue baby syndrome may cause signs
similar to a cold or other infection (fussy, tired, diarrhea or
vomiting). While there is a blood test to see if an infant has
blue baby syndrome, doctors may not think to do this test for
babies with mild to moderate symptoms.
What should I do if my infant has blue baby syndrome?
Take a baby who has brownish-blue skin tone or a bluish color
to the lips, tongue, gums, nail beds, or nose to a hospital
immediately. A medication called “methylene blue” will quickly
return the baby’s blood to normal.
Can I prevent blue baby syndrome?
Yes. Do not give infants younger than 12 months drinking
water with nitrate levels above 10 mg/L. Do not offer
high-nitrate vegetables such as beets, broccoli, carrots,
cauliflower, green beans, spinach, and turnips until the baby is
at least seven months old.
Nitrate levels in well water can vary throughout the year. If
you have a private well and you’re not sure about your water
quality, you may want to use bottled water to prepare your
baby’s food and drinks. Although boiling water kills bacteria,
it will not remove chemicals such as nitrate. In fact, boiling
may actually increase the nitrate level.
Will breast-feeding give my infant blue baby syndrome?
Low levels of nitrate have been found in breast milk, but the
levels are not high enough to cause blue baby syndrome.
Can nitrate affect adults?
Although red blood cells quickly return to normal, some
health conditions can make people more susceptible to health
problems from nitrate. Individuals with the following health
conditions should not drink water with more than 10 mg/L of
nitrate:
- Individuals who don’t have enough stomach acids.
- Individuals with an inherited lack of the enzyme that
converts affected red blood cells back to normal (methemoglobin
reductase).
- Women who are pregnant or trying to become pregnant.
High nitrate levels may increase the risk of spontaneous
abortion or certain birth defects.
How can I tell if my well water has nitrate?
Shallow wells, poorly sealed or poorly constructed wells, and
wells that draw from shallow aquifers are at greatest risk of
nitrate contamination. Manure and septic tank waste may also
contain disease-causing bacteria and viruses.
If you own a private well, we recommend that you test for
coliform bacteria and nitrate every year. Your county health
department can tell you where you can get your water tested and
may have specific recommendations for testing. Many certified
labs in Washington charge $20 to $40 per test. If your nitrate
test results are 5 mg/L or higher, you may want to re-sample in
six months.
Where can I get more information?
If you get your water from a public water system, call
your water utility or the state Department of Health at (800)
521-0323.
If you have a private well, call your local health
department. You can also find information in Private Wells:
Information for owners (331-249) a publication available in
English and Spanish at
https://fortress.wa.gov/doh/eh/dw/publications/publications.cfm
For a list of certified labs, visit the state
Department of Ecology. Under "Location," select your state,
city, and county. Scroll down and click on "Show results." Click
on the name of a lab to see the tests it performs. Call the lab
to make sure it's accredited to analyze for nitrate in drinking
water.
If you need this publication in alternate format, call (800)
525-0127. For TTY/TDD, call (800) 833-6388.
June 2010
DOH 331-214 (Revised)
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