Cause of Water Pollution
Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers. Sewage disposal is a major problem in developing countries as many people in these areas don’t have access to sanitary conditions and clean water. Untreated sewage water in such areas can contaminate the environment and cause diseases such as diarrhea. Sewage is treated in water treatment plants and the waste is often disposed into the sea. Sewage is mainly biodegradable and most of it is broken down in the environment. In developed countries, sewage often causes problems when people flush chemical and pharmaceutical substances down the toilet. When people are ill, sewage often carries harmful viruses and bacteria into the environment causing health problems.
Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping.Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping, cause a very localized problem but can be catastrophic to local marine wildlife such as fish, birds and sea otters. Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.