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Copper and Zinc

Although copper and zinc are non-toxic in small amounts and are beneficial as well as
essential for humans, animals and plants. Zinc in high concentration imparts milky color to

water. Zinc toxicity in humans results in abdominal pain, vomiting, electrolyte imbalance and
dehydration [1, 13, 23].

Biochemical Oxygen Demand (BOD)
The amount of oxygen dissolved in water and needed by aerobic micro-organisms to degrade

organic matter in specific amount of water under specific time period is called Biochemical

oxygen demand (BOD). Which means more the organic material in the water more is the
BOD and more is the pollution [18].

Chemical Oxygen Demand (COD)

It is the amount of oxygen needed for oxidation of organic matter chemically by using
chemical oxidant. COD has an advantage over BOD of being quicker in estimating organic

contamination in water [1].
Biological Parameters

As a standard, drinking water should not contain any disease causing microorganisms,
indicative of faecal contamination. The drinking water should not contain any E. coli or

thermo tolerant coli form bacteria [25].

Coliform bacteria are present in the surrounding environment and in the faeces of humans
and animals. Most of the coliform bacteria do not cause illness, but they are indicative of the

fact that other disease inducing organisms may be present in the water. The symptoms of
waterborne infection include nausea, vomiting, and diarrhoea. Person of all age groups viz

infants, elders, or those with weakened immunity may suffer from more severe effects. Under
critical conditions some pathogens may affect important body organs such as skin, lungs,

liver, nervous system, eyes or kidneys and the effects may prove to be chronic, or fatal.

Coliform bacteria are not naturally present in groundwater; however, but they (bacteria) can
live within slimy habitats formed by naturally existing ground water microorganisms. This

slimy layer hold on to the well’s screens, and pumps, which gets dislodged due to

disturbances caused during construction or maintenance of well, making the coliform bacteria
to get released into the water [26].

Sources of coliform bacteria contamination [27]:
 Missing or defective well cap

 Cracks or holes in the well casing

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