The quality of drinking water strongly varies from one area to another. Numerous environmental and industrial factors change the basic characteristics of drinking water and make it unsafe for consumption. In developed countries, special agencies and organizations control the quality of drinking water and keep population informed if any danger arises. People in the third-world countries are rather uninformed and exposed to the danger hidden in a visibly clear transparent substance.
Type and level of contamination of drinking water depends on techniques used for its cleaning and transportation. In some African regions where sanitation facilities are very archaic and do not separate wastes from leaking into fresh water, biological contaminants are excessive. They cause epidemics of gastrointestinal diseases and increase mortality among the population. People in rural areas normally use wells and rivers as the source of fresh water, however, they may be naturally contaminated with blue-green algae or cyanobacteria.
Chemical contaminants affect the quality of fresh water in a wide range of countries, including the developed world. First of all, chemicals that naturally occur in any particular area interact with groundwater and store in the human body. Waterborne arsenic frequently comes unnoticed and causes cancer and disrupts functioning of organs. It commonly occurs in Asian countries and in South America. The same refers to waterborne fluoride that causes fracture of bones and various skeletal deformations. Some chemicals occur in drinking water because of the human negligence. Chemicals from industrial spillages and untreated e-waste easily interact with water and pose danger for the local population. Frequently, water pipes in developing countries are mended with toxic metals that cause mass contamination.