What are the sources of water pollution?

Sources of Water Pollution

There are many types of pollutants, with some being more common and well-known. These include acids that reach wastewater through mining, pollutants carried by agricultural runoff, sewage water, and dredging operations. Water pollutants are categorized based on how they enter the environment into point-source pollutants and non-point-source pollutants.

Point-Source Pollutants

A pollution source is classified as a point source when the pollutant enters water from a specific or easily identifiable source, such as a leaking tank or a waste pipe. According to the U.S. Environmental Protection Agency (EPA), a point-source pollutant is any single identifiable source that causes pollutants to enter water, such as:

• Industrial Waste:
  • Refineries
  • Paper mills
  • Automotive factories
  • Chemical factories
  • Food and pharmaceutical industries
  • Notable pollutants include:
    • Oils
    • Thermal pollutants
    • Toxic chemicals
    • Heavy metals
    • Pharmaceutical residues
• Wastewater Treatment Plants and Sewer Discharge:
  • Major pollutants include:
    • Bacteria
    • Harmful nutrients

Non-Point-Source Pollutants

Non-point-source pollution generally arises from multiple sources, such as surface water runoff, rainfall, drainage, or snowmelt. Unlike point sources, non-point-source pollutants are harder to pinpoint because they originate from widespread areas. Polluted water from non-point sources often ends up in rivers, lakes, seas, coastal waters, wetlands, or groundwater.

Many countries identify non-point-source pollution as a major cause of water quality issues. The challenge with these sources lies in their variability and difficulty in identification. These pollutants negatively impact drinking water sources, recreational waters, fish populations, and wildlife.

Examples of Non-Point-Source Pollutants:

1. Toxic Pollutants:
   • Include heavy metals like mercury, lead, and cadmium, as well as organic compounds like polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and flame retardants (e.g., polybrominated diphenyl ethers – PBDEs). These substances resist breakdown, posing risks to humans and aquatic organisms.
   • Sources include:
     • Fossil fuel combustion plants
     • Pesticides
     • Industrial waste
     • Oil spills
     • Vehicle emissions
2. Sediments:
   • Result from soil erosion or sand movement in construction sites, agricultural fields, or riverbanks. Sediments may carry harmful pollutants and damage water sources.
3. Nutrients:
   • Substances like phosphorus and nitrogen are essential for plant growth, but their excessive presence in drinking water can cause pollution. They promote excessive aquatic plant growth, reducing dissolved oxygen levels.
   • Sources include:
     • Animal waste
     • Fertilizers
     • Malfunctioning septic systems
4. Pathogens:
   • Include disease-causing bacteria and viruses that contaminate drinking water, threatening human and animal health.
   • Sources include:
     • Leaking septic tanks
     • Damaged sewer pipes
     • Livestock feeding stations
5. Debris:
   • Refers to garbage and plastics that threaten marine life and reduce the aesthetic and recreational value of water bodies.
   • Sources include:
     • Illegal waste dumping
     • Littering in streets and beaches
     • Trash from boats
6. Thermal Stress:
   • Refers to an increase in water temperature, which is harmful to native species and fosters the growth of invasive species.
   • Sources include:
     • Runoff from heat-absorbing surfaces like pavements
     • Removal of vegetation along riverbanks
7. Other Pollutants:
   • Include fertilizers, pesticides, herbicides, and excessive salts from irrigated lands, as well as acids that enter sewage from mines.

What is Dredging?

Dredging is the process of removing silt and sediments from the bottoms of lakes, rivers, and other water bodies to facilitate navigation for ships and boats.

What is Water Pollution?

Water pollution refers to the presence of physical, chemical, or biological substances in water in excessive amounts, altering its quality and harming living organisms. Unpolluted water is colorless, odorless, and tasteless, while polluted water may have an unpleasant taste, odor, or cloudy appearance. Some pollutants, such as pesticides and microscopic organisms, are not visible to the naked eye.

Contaminated water should not be used for drinking, agriculture, bathing, or washing, as it can negatively affect human health in various ways depending on the type and concentration of the pollutant.