The water may contain clay, sand and other impurities. A major danger of water contamination is, for example, in the presence of Toxic chemical products or microorganisms that make the water polluted.
There are several sources of pollution, as we will see below.
The consequence of lack of sewage treatment
The large number of waste from the populous residential nuclei discharged into streams, rivers and seas causes pollution and water contamination. Typhoid, hepatitis, cholera and many worms are diseases transmitted by these waters.
There are rivers such as Tietê and Guaíba - on whose banks the city of São Paulo and Porto Alegre emerged - that are already compromised. In addition to these, there are several rivers exposed to environmental degradation.
Tietê in works in São Paulo to remove deposited garbage.
Mining, extraction and oil transportation
Major economic activities have caused numerous serious ecological accidents. Petroleum extracted from the seas and the heavy metals used in mining (eg mercury in the Pantanal), thrown into the water by accident, or negligence, have caused water pollution with often irreversible environmental damage.
Oil spill occurred in Guanabara Bay, Rio de Janeiro, Jun. 2000
Pollution from industries
Even though there are laws prohibiting many industries, they continue to throw toxic waste in large quantities into rivers.
On the surface of the water, it is common to form a small acid foam, which, depending on the source of pollution, may be composed mainly of lead and Mercury. This foam can cause the flora and fauna of these rivers to die. And these polluting agents also contaminate the fish-eating organism or any other products from those waters.
Accident in Rio dos Sinos where thousands of fish died from contamination of the river with chemical waste released by companies, Rio Grande do Sul, October, 2006.