Testing of Private Wells
About half the population of Michigan depends on
ground water as the primary source of drinking water.
Many of these individuals, especially those residing in
rural areas, have their own wells. In light of recent
reports of groundwater contamination in many areas of the
state, much concern exists about the safety of well
water. This is designed to address this concern and
provide a guide to testing private wells.
Many contaminants are natural. Where do these
contaminants come from? Many are naturally occurring
substances such as calcium, magnesium, silica and
fluoride. As many as 50 minerals may naturally occur in
water but these generally do not cause health problems,
since they usually occur in such small amounts. More
often they impart undesirable properties such as
unpleasant taste, odor or hardness to the water.
Some contaminants are living organisms, mainly soil
bacteria. The ones which cause the most common odor,
taste, smell and discoloration problems are the sulfur,
iron and manganese bacteria. Occasionally other types of
bacteria, which indicate unsanitary conditions, are
present. These may not affect the characteristics of
water but are indicators of the possible presence of
disease-causing microorganisms.
Other contaminants are man-made. These include a wide
range of synthetic organic compounds, such as
trichloroethylene, phenols, benzene and toluene. Other
chemicals which may contaminate water are the heavy
metals such as lead and cadmium, and salt or brine used
on roads. In general, these contaminants pollute
groundwater as a result of improper storage or disposal
practices. Leaking underground storage tanks and leaking
landfills are two common examples. At high-enough levels,
these contaminants may render water unsuitable for
drinking and may cause adverse effects on health.
Tests of well water have to be very specific. It is not
possible to test one well and determine what the
contaminant levels are in other wells in that area. A
very complex hydrogeological investigation would be
needed to make this determination, and this is not
generally cost-effective. Thus, it is usually up to the
individual well owner to decide if well testing is needed
and what particular tests should be performed.
If well-water quality is in doubt, the first thing
that a well owner should do is to contact the local
health department. Department sanitarians can discuss the
problem and recommend further action. ln some cases, a
visit to the well site will be needed before a decision
can be reached. If the situation warrants it, water
testing may be the next step. This testing may be done by
the local health department, by the state health
department or by a private testing firm. Many tests can
be done by the appropriate agency, but private testing
may be needed due to the limited resources available in
these agencies. The agencies work on a priority system,
which takes into account both the potential health risk
and the number of people who may be affected.
Sampling is the first step. Regardless of who
performs the testing the first step is the collection of
the water sample. If the well owner performs the
sampling, he or she is usually provided with the
appropriate sterilized sample bottle and instruction on
how, when and where to collect the sample. This is a
crucial step, since the contaminants are generally
present in very minute amounts, and careless sampling can
destroy the possibility of obtaining accurate results.
Once the sample is obtained, it may be tested for a
number of different types of contaminants. One type of
test is designed to detect bacterial contamination. Most
odor, taste, smell and discoloration problems are due to
bacteria, so this test is performed quite commonly. It is
usually done free of charge by the local health
department. A second type of analysis, a partial chemical
analysis, is used to detect commonly occurring inorganic
constituents, such as magnesium, calcium, sodium, iron,
fluoride, chloride and nitrate. Some of these, such as
fluoride and nitrate, may be health hazards at high-
enough levels. Others, such as magnesium and iron, are
usually of concern due only to their effects on. This
type of test is more expensive than the bacteriological
analysis, but it is still not very costly. A third, and
potentially very expensive, type of analysis is a
specific chemical analysis. This is used to look for one
or a few particular chemicals which are suspected of
being present in the water. It is not possible to simply
analyze water for everything; the well owner must narrow
down the possible sources of the problem so that a
limited set of tests can be conducted. Some of the most
common types of specific chemical analyses are:
1. Purgeable halocarbons - These include many solvents
such as paint strippers and degreasers.
2. Purgeable aromatics - Petroleum products, such as
paint thinner, gasoline and fuel oil.
3. Non-volatile organics - Many pesticides.
4. Total organic halogen - Organic chemicals containing
chlorine or bromine.
5. Total organic carbon - Organic compounds and the
existence of a class of contaminants.
Once the tests are completed, the well owner is faced
with interpreting any positive results. The presence of a
contaminant is not always an indication of a health
hazard. It is the level at which it is found that is most
important. Although there are no established levels for
private well water, the levels established for public
supplies can be used as guides. It is best to discuss
results with a sanitarian from the local health
department, since he or she will have these established
levels available and can help you interpret your results.
If the well owner finds that the well is contaminated
with levels that might have significant health effects,
the well should not be used. At this point there are five
basic alternatives: install a new well, connect with a
public system (if available), use bottled water, install
filters, or move to another area.
Drilling a new well may not solve the problem if it
is drilled into the same aquifer, if the contaminant has
also polluted the deeper aquifer, or if the source of
contamination has not been identified. It is also
expensive. Bottled water is generally just a temporary
solution. In addition to the expense, the quality of
bottled water not always assured although the Michigan
Department of Public Health (MDPH) monitors the source
and the Michigan Department of Agriculture (MDA) inspects
bottling plants. Installation of filters may appear to be
an attractive solution but it also has drawbacks. These
devices are unregulated and thus vary in effectiveness;
they require careful maintenance and generally lack
malfunction indicators. Filters are usually not
recommended by health agencies.
The last solution, moving to another location, is a
drastic one but may be necessary in extreme situations.
Most people assume that scientists have a good
understanding of the health effects of water
contaminants. Unfortunately, this is not the case for
many substances found in well water. As a result, the
well owner is often faced with uncertainty in the
interpretation of contamination which may occur.
Discussion with appropriate health officials should
reduce this uncertainty, but it must be understood that
difficult decisions may be necessary.
The scientific community is working on these
problems, but it will undoubtedly be a long time before
the health effects of all water contaminants can be
predicted with confidence.