Water pollution is the contamination of water sources by substances that make the water unusable for drinking, cooking, cleaning, swimming, and other activities. Pollutants include chemicals, trash, bacteria, and parasites. Water pollution can occur in various ways, including:
- Agricultural runoff: Toxic substances from farms, towns, and factories readily dissolve into and mix with water, causing water pollution.
- Air pollution: Air pollution settles onto lakes and oceans.
- Land pollution: Waste dumped in a vacant lot can eventually pollute a water supply.
Water pollutants may cause disease or act as poisons. Bacteria and parasites in poorly treated sewage may enter drinking water supplies and cause digestive problems such as cholera and diarrhea. Hazardous chemicals, pesticides, and herbicides from industries, farms, homes, and golf courses can cause acute toxicity and immediate death, or chronic toxicity that can lead to neurological problems or cancers. The main water pollutants include bacteria, viruses, parasites, fertilizers, pesticides, pharmaceutical products, nitrates, phosphates, plastics, faecal waste, and even radioactive substances. Water pollution can have devastating effects on aquatic ecosystems and can also seep through and reach groundwater, which might end up in households as contaminated water used in daily activities, including drinking.
