Bacteriological Analysis (Safe or Unsafe)
Learn how to take bacteriological samples
If your bacteriological analysis is determined to be unsafe for drinking purposes, it means there are
organisms of the coliform group present in your water. These organisms are characteristic of sewage,
sewage-like materials and surface drainage. Until your well is tested and found to be safe, the water
should be boiled before being used for drinking purposes.
Shallow and deep wells are most often contaminated by means of surface water which enters around the
pump, through the well cover, or through the upper few feet of the well casing.
Wells are sometimes terminated in pits for the purposes of preventing freezing during cold weather. These
pits will often collect surface waters which may enter the well by overflowing into the casing or by
seeping down the outside of the casing and then into the water bearing formation. It is possible for water
to seep down the outside of the casing a considerable distance without the bacteria being filtered out,
since the space between the drill hole and the casing often has not been completely filled in. From a
sanitary viewpoint, well pits are not desirable.
Go to: Disinfecting Your Well
It is recommended that the bacteriological quality of the water be retested at least annually. After
heavy rains, snow melt, or flooding in the area of your well, a sample of water should be submitted for at
least a bacteriological and nitrate analysis
Chloride in drinking water is generally not harmful to people until high concentrations are reached,
although chloride may be injurious to some people suffering from diseases of the heart or kidneys.
Restrictions on chloride concentrations in drinking water are generally based on taste requirements rather
than on health. The source of chloride may be a more important factor than the quantity of chloride; any
sudden increase in the chloride content should be suspected as a possible indication of pollution and
should be investigated further. Chloride should not exceed 250 mg/L (milligrams per liter).
Copper is currently regulated because of its effect on the taste of drinking water. Copper is an essential
nutrient, but there is no evidence of copper deficiency in the U.S. population. Toxic effects from
elevated drinking water levels have been reported, especially from infants. Copper imparts an unpleasant
taste to drinking water, which along with an emetic (induces vomiting) effect, serves to limit the amount
of copper which can be ingested from drinking water. The occurrence of copper in drinking water is usually
a result of corrosion. The recommended maximum limit is 1 mg/L.
Iron and Manganese
|Iron and manganese are nuisance chemicals that cause troublesome stains and
deposits on light-colored clothing, plumbing fixtures, and in pipes. Iron causes yellow, red, or
reddish-brown stains and deposits while manganese stains and deposits are gray or black. Iron and
manganese can be removed in a zeolite softener equipped with a special resin or by small treatment systems
using aeration, filtration, and chlorination. Manganese in excess of 0.05 mg/L will more than likely cause
problems. Iron problems arise with levels greater than 0.3 mg/L, or a combination of iron and manganese in
excess of 0.3 mg/L. Iron and manganese may also contribute to odor problems.
|Water with a sulfate content in excess of 250 mg/L may have a bitter taste and
have a laxative effect on persons not adapted to the water. Sulfate may contribute to odor problems. The
sulfate content can be reduced in a private water supply through treatment.
|Zinc is currently regulated based on taste considerations. Zinc occurrence in
drinking water is most frequently due to the corrosion of galvanized ion pipe and fittings. Zinc is
relatively non-toxic and is and essential trace element. At drinking water concentrations high enough to
cause gastrointestinal problems, zinc would impart a strong astringent (puckery) taste and milky
appearance to the water. The recommended maximum limit is 5 mg/L.
|This refers to the amount of total solid matter suspended and dissolved in
water. Water with a high solids content is generally a poor quality drinking water. A limit of 500 mg/L
for drinking water is recommended with 4,000 mg/L as a maximum.
|The pH indicates the acidity of the drinking water. The pH scale is from 0 to 14
units with a value of 7 being neutral (equal amounts of acid and base). pH values less than 7 are acidic,
and pH values above 7 are basic (alkaline). The recommended limit for pH is 6.5 - 8.5.
|Alkalinity is not considered to be detrimental to humans, but is generally
associated with hardness, high pH values, and excessive dissolved solids, all of which may be undesirable.
No recommended standard has been set.
|Excessive bicarbonate adds to the salinity and total solids content of water,
and at high temperatures tends to form scale deposits on faucets and other plumbing. No recommended
standard has been set.
|This term is also called temporary hardness because heating will remove it. When
water is heated, bicarbonate breaks down into carbonate and forms solid particles that can stick to in the
inside of pipes or a heated surface.
|This measures the ability of water to conduct an electrical current, and is
related to the type and amount of dissolved chemicals in water. In general, water having a conductivity of
less than 1,000 microohms may have slight hardness as well as taste and odor problems. Dependent upon the
particular chemicals dissolved in the water, these problems may become more pronounced with increasing
conductivity to the extent that levels greater than 2,000 microohms may make the water objectionable for
|Calcium is essential to human nutrition and a key element in the formation of
teeth and bones. Calcium is also know as limestone and is a cause of water hardness that creates soap curd
and scum in sinks and bathtubs. It forms scale deposits in water pipes, water heaters, and tea kettles.
Calcium is removed by use of a home water softener.
|Magnesium is one of the most common elements in the earth's crust. It is used as
an antacid medicine. Salts of magnesium and calcium are a cause of water hardness and both can be removed
by a home water softener. Magnesium sulfate at very high concentrations (above 1,000 mg/L) may have a
laxative effect on some people that are unaccustomed to drinking the water and will also give water an
|This value indicates whether the water tends to be corrosive (-) or deposit
|Sodium may be of health significance to individuals on a low-salt diet. The
sodium content is increased when water is passed through a home water softener. People on low sodium diets
should consult their physician as to how much water may be consumed.
Hardness is the soap consuming capacity of water. The harder the water, the more soap is required to
produce a lather. Hard water also causes greasy rings on bathtubs, sinks, and dishes, scale deposits in
pipes and faucets, and poor laundry results. Hard water problems may be partially overcome for bathing
and washing by the use of synthetic detergents or packaged "softening" compounds. The hardness of water
may be reduced by use of a home water softener. Home water softeners increase the sodium content of
water and therefore may be of concern to people on low sodium diets. Home water softeners do not reduce
the total dissolved solids, nitrate, sulfate, or fluoride level of the water. Note that
17.12 mg/L equal 1 grain per gallon. South Dakota water is rated for hardness as follows:
0 -3 grains per gallon - soft water
4 - 10 grains per gallon - reasonably soft water
11 - 25 grains per gallon - fairly hard, less than average for SD
26 - 50 grains per gallon - average hardness for SD
51 - 75 grains per gallon - very hard
Over 75 grains per gallon - extremely hard
|In public drinking water supplies, potassium is an essential nutritional
element, but in excessive quantities it acts as a laxative, and 1,000 to 2,000 mg/L is regarded as the
extreme limit of potassium permissible in drinking water.
|Nitrate is excess of 10 mg/L (as nitrogen) is of health significance to infants
of six (6) months of age or less, and pregnant women. High nitrate water should not be used for infant
feeding or formula preparation. Nitrate cannot be removed or reduced by boiling. Boiling will actually
increase the concentration of nitrate in the water.
Fluoride is common in nature and is therefore a common component of drinking water. At certain
concentrations (1.2 mg/L in SD), fluoride is beneficial by reducing dental cavities significantly. Higher
levels of fluoride in water (above 4.0 mg/L) can cause mottled or stained teeth in children that drink the
water for long periods before their permanent teeth are in place. This mottling can cause the teeth to be
more fragile and sometimes lead to increased cavities. Osteoporosis (leaching of calcium from the bones)
can also be caused by high levels of fluoride in drinking water.