When should I get my water tested and how often?
Generally, private water supplies should be tested for nitrate and bacterial contamination
annually. Otherwise, drinking water should be tested if:
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you notice a change in your water quality.
people using the water suffer from an illness which may be waterborne.
there is a flood or large storm that may have carried contaminants to your
wellhead.
maintenance work is done on the well.
a pregnant woman, a woman anticipating pregnancy, or an infant under the age of
six months becomes a water user.
It is best to do coliform bacteria tests in the spring during wet weather. This is when
bacteria are most likely to be found because runoff and excess soil moisture can carry
contaminants into shallow groundwater sources or through well defects. Testing during
dry weather or when the ground is frozen may not indicate the presence of bacteria
because they are likely to be at lower concentrations under these conditions.
The Federal Centers for Disease Control and Prevention (CDC)
have reported that consumption of contaminated drinking water in the
United States has resulted in thousands of cases of illness each year.
Contaminated drinking water can cause a number of diseases, and is
sometimes fatal. The most common contaminants are microbes and
nitrate.
Microbes: Many types of bacteria themselves are generally not harmful,
but their presence is an indication that other harmful bacteria, viruses,
or parasites may also be present. Diarrhea, nausea, and vomiting are some
of the most common symptoms resulting from drinking water that is
contaminated with harmful bacteria. Total coliform bacteria are microbes found in the digestive systems of
warm blooded animals, in soil, on plants, and in surface water. These microbes typically do no make you
sick; however, because microbes that do cause disease are hard to test for in the water, total coliforms are
tested instead. If total coliform is present then it is possible that harmful germs like viruses, bacteria, and
parasites might also be found in the water. Fecal coliform bacteria are a kind of total coliform. The feces
(or stool) and digestive systems of humans and warm-blooded animals contain millions of fecal coliforms.
E. coli is part of the fecal coliform group. Fecal coliforms and E. coli are usually harmless. However a
positive test may mean feces and harmful germs have found their way into your water system. These
harmful germs can cause diarrhea, dysentery, and hepatitis. It is important not to confuse the test for the
common and usually harmless E. coli with a test for the more dangerous E. coli 0157:H7. By using the
Colilert method for testing drinking water both total coliform and E. coli can be tested for at the same time.
Nitrate (DOH): High levels of nitrate in drinking water can pose an immediate
threat to infant children. When consumed, nitrate is known to react with hemoglobin
in the blood causing an anemic condition known as the "blue baby syndrome."
To ensure that your private water supply is safe and healthy, you should
understand the importance of maintaining your own well and water system
and performing routine water quality tests.
Test Your Well Water Every Year - It's Simple and Inexpensive
If you have a private well, the Department strongly recommends that you test your water for bacteria and
nitrate at least once per year. Routine water testing is a simple and inexpensive measure you can take to
ensure that your water supply is safe and to protect your family's health. Our county health department can
provide you with instructions on how to collect the water samples yourself and to have them tested (usually
$12-20 per sample). In some cases, health department staff can come to your home and collect the samples
for you, if you wish, for an additional fee.
While bacteria and nitrate are the most common threats to your drinking water, your water well
may also be susceptible to other contaminants. Depending on past and present land-use
activities or other sources of contamination in your neighborhood, additional water tests may
be recommended by the department. In some cases, the health department may be able to do
testing for certain toxic substances free of charge
The health department can help you understand your test results and advise you on measures you should
take should the results show that your well water is contaminated. You may need to disinfect your well,
repair your water system, or install treatment equipment.