Any toxic or foreign material entering the water can be considered as a form of water pollution. Contamination of drinking water has been associated with gastrointestinal disorders, the spread of certain diseases, and sometimes death in severe cases. Younger children, babies and elder people are especially vulnerable to water borne pollution,. The parasites may be present in drinking water supplies. When visiting a developing country, tourists are advised to bring bottled water from elsewhere to avoid the consumption of local supplies which may have a number of microbes which can cause health problems for the tourist. Local people may be able to drink polluted water without being affected. .
Cast Water quality
Most of the sources of water pollution in industrialized countries are from chemical contamination, either from the deposit of chemicals in soil or drains, or through accidental spills. Oil spills, for example, can occur in wells inland or on sea going vessels and can pollute the water at a distance of miles from the spill. Industrial factories also dump untreated waste into the water, although this is rare in developed countries due to strict government regulations regarding the disposal of hazardous materials.In developing countries untreated industrial waste will be the major cause of pollution as the regulators are often tax while monitoring polluting industries.