Water pollution happens when undesired and unwanted chemicals are introduced into water bodies, suffocating the aquatic life that lives there.
The following are the primary sources of water pollutants:
| Pollutant | Source |
| Organic wastes | Domestic sewage, discharge from food processing industries, animalexcreta and waste, decaying animals and plants
|
| Micro-organisms | Domestic sewage |
| Sediments | Strip mining and soil erosion |
| Plant nutrients | Chemical fertilizers |
| Radioactive substances | Mining of uranium ores |
| Pesticides | Chemicals used for killing fungi, weed, insects |
| Toxic heavy metals | Chemical factories and industries |
| Heat | Water used for cooling in industries |
The following are the main pollutants:
1. Pathogens: This group includes bacteria and other microorganisms. Domestic sewage and animal excrement are two ways they enter into water bodies. Bacteria present in human excreta, such as Escherichia coli and Streptococcus faecalis, are known carriers of gastrointestinal illnesses.
2. Organic wastes: Organic wastes are biodegradable wastes that contaminate water bodies by combining with them during discharge. Excess organic matter in water bodies suffocates dissolved oxygen in the water, preventing aquatic life from flourishing.
Heavy metals such as mercury, cadmium, and nickel are examples of chemical pollutants
