Water is a necessity to life on earth. All organisms contain it, some drink it, and others inhabit it. Plants and animals require water that is moderately pure, and they cannot survive if their water is affluent with toxic chemicals and/or harmful microorganisms. If severe, water pollution can kill large numbers of fish, birds, and other animals, in some cases killing all members of a species in an affected area. Water pollution is not only hazardous to water-bond animals it also poses as threat to humans as well.
The majority of water pollution occurs when people overload the water environment with wastes. It's defined as contamination of streams, lakes, underground water, bays or oceans by substances harmful to living things. Such things as oil spills, boat fumes, and dumping of trash into the oceans, lakes, and rivers are just a few of the major contributors to water pollution. Throughout the past century water pollution has become a very real problem and solution must be found.
First of all, Water pollution presents problems to humans in a few ways. Water pollution makes streams, lakes, and coastal waters unpleasant to look at, to smell, and to swim in, as well as preventing us from drinking it without filtration. Fish and shellfish harvested from polluted waters may be unsafe to eat. People who ingest polluted water can become ill and if they're exposed for a long time, may develop cancers, or have children with birth defects.
There are two types of water pollution; point source and non-point source. Point sources of pollution occur when harmful substances are put directly into a body of water (such as an oil spill). A non-point source is when pollutants enter the water indirectly through environmental changes (like when fertilizer is carried into a stream by rain).