ABSTRACT
Although three-quarters of the earth’s surface is water, only 1% is available for direct use, including drinking, and this often requires treatment before it can be used safely. Water contains many kinds of microbes and organisms, which can cause disease. It is estimated that 80% of all sickness and disease in developing countries is caused by unsafe water and inadequate sanitation. Waterborne diseases continue to present challenges to public health ofcials and water suppliers. Prevention and control of waterborne diseases through water source protection and proper treatment techniques are critically important. Untreated or inadequately treated drinking water supplies, primarily from surface water sources, contain microorganisms that can cause outbreaks of waterborne diseases. There are new concerns about emerging pathogens, including protozoa like Giardia, Cryptosporidium, and certain viruses that might be found even in drinking water treated by conventional methods. Vulnerable populations such as the young, the elderly, and those with compromised immune systems remain at risk for signicant illness and even death. If left untreated, drinking water supplies (primarily from surface water sources) will cause waterborne diseases such as cholera, typhoid, and dysentery. Over the last century, it has been observed that water use has increased at more than double the rate of population rise. It has been predicted by the United Nations that 1800 million people will be living in regions of absolute water scarcity and two-thirds of the world population could be under stress conditions by the year 2025. The water withdrawals by the developing countries would increase to 50%, and those by developed countries would be around 18% (Water Use, 2012).
