Page 2 - 2. Lesson notes- Water; water pollution

WATER POLLUTION:

Water pollution is the contamination of water bodies, usually as a result of human activities.
Water bodies include for example lakes, rivers, oceans, aquifers and groundwater.

“Water pollution is an undesirable change in the physical, chemical or biological composition
of water which makes it unfit for consumption by living organisms.”

Causes of water pollution:

1.Pathogens
One of the most severe pollutants is the disease-causing microorganisms called pathogens.

Pathogens are mostly bacteria, viruses, and protozoa. A few of pathogenic bacteria as well

which enter the water bodies through sewers and sanitation systems. The water-borne
pathogens cause several diseases such as diarrhea, gastrointestinal illness, etc.

2.Organic Wastes

Organic water pollutants include food waste, detergents, leaves, grass, etc. They originate from

domestic sewage, discharge from food processing factories and farm wastes which reach the
water sources through runoff and pollute them.

BOD (Biological oxygen demand)

Bacteria decompose the complex organic matter into simple organic matter. They consume

oxygen which is dissolved in water. As the organic waste content in the water increases so