Water related diseases affect all aspects of water use, most importantly, drinking water and water for bathing and sanitary purposes. As a result, it is really difficult to imagine how microbes can be totally eradicated from water used in developing countries.
It is equally puzzling to imagine a problem with the water in the developed world. Technology exists in the developed world to completely eradicate any risk from water used for: bathing, cooking, drinking, and in the production of a myriad of products.
The question then is what would it take to eradicate waterborne diseases in the developed world? When you consider the way people interact with their water supply and when you consider the significant shortages of clean water in these countries, it should come as no surprise that there are significant diseases contracted from the water supply in these countries. Some of these waters happen to be contaminated with human waste, and at the same time, the same water supply is used to clean clothing, bathe, cook, and as a source of drinking water.
As long as water continues to be accessed from rivers, streams and ponds, and not from a public utility, it is impossible to ensure that the water supply is completely clean. Even if science were to provide a solution via a pill or some other means by which those accessing the water from streams and rivers can add this pill to the water before they use it; how exactly is compliance guaranteed amongst users of these waters?
In the developed world, most public water utility systems utilize various techniques to ensure that the public water supply is free from microbes; in the U.S. in most states fluoride is used in the water. Even beyond the measures taken by the public water utilities, individuals who want extra assurance can easily purchase water purification systems that utilize both ultraviolet radiation (UV) and filters or membranes the exclude microbes above 0.2 micrometers. A combination of both UV and the filters has been demonstrated to be very effective. However this is a relatively expensive option, and is beyond the reach of most middle to low-income countries, as a result, it is not a viable option for these countries.
I remain optimistic about the possibilities for a solution to the waterborne diseases in developing countries. I believe science will conquer water-related disease, but not in my lifetime. Before waterborne disease can be eradicated in developing countries, the structural problems that these countries face, along with the rampant poverty have to be resolved first.