El Zorro, check out these links below.
This issue is not simply one of SA being 3rd world and having poor water. There are many instances where water in Southern Chile, for example, may be naturally more pure than what we have in the US.
If you look deeper you will find that most US big cities dont even meet the guidelines and its a topic that is rarely discussed here. Even Switzerland has issues, amongst the cleanest of all countries in the world.
There are many organic and inorganic metals, etc that exist naturally in the earth that appear with erosion and are washed into rivers as well as acid rain to name a very few.
Here are some quotes and a link:
"Environment Protection Agency of The United States of America has estimated that some 13 million of the population of USA, mostly in the western states, are exposed to arsenic in drinking- water at 0.01 mg/L, although concentrations appear to be typically much lower than those encountered in areas such as Bangladesh and West Bengal. (USEPA, 2001) "
"# Arsenic is widely distributed throughout the earth's crust.
# Arsenic is introduced into water through the dissolution of minerals and ores, and concentrations in groundwater in some areas are elevated as a result of erosion from local rocks.
# Industrial effluents also contribute arsenic to water in some areas.
# Arsenic is also used commercially e.g. in alloying agents and wood preservatives.
# Combustion of fossil fuels is a source of arsenic in the environment through disperse atmospheric deposition.
# Inorganic arsenic can occur in the environment in several forms but in natural waters, and thus in drinking-water, it is mostly found as trivalent arsenite (As(III)) or pentavalent arsenate (As (V)). Organic arsenic species, abundant in seafood, are very much less harmful to health, and are readily eliminated by the body. "http://wwf.org.au/publications/rich-cou ... -water.pdf
Read page 9 of the above about the USA.