One of the defining differences between the developed and developing countries in the world today is the provision of access to safe drinking water. Worldwide, >1 billion people have no alternative but to drink contaminated water. The result is an ≈50 million deaths annually and an incidence of a host of waterborne diseases that are rarely seen in the developed world. Cholera, for example, will kill half of all infected people if left untreated. Even the more advanced drinking water treatment technologies, such as chlorination, fail to provide complete protection against some pathogens such as cryptosporidium. Effective water and wastewater treatment technologies are expensive, and the necessity of tailoring them to site-specific circumstances increases the cost even more. For the poorest countries of the world, the high cost means that these technologies are not viable.