Inadequate and, oftentimes, contaminated drinking water has severely impacted the health of populations in many countries. Some of the countries with significant populations whose only consumption is of contaminated water include Sudan (12.3 million), Iran (5.6 million), Venezuela (5.0 million), Syria (3.8 million), Zimbabwe (2.7 million), Tunisia (2.1 million), and Cuba (1,2 million). (Source: Wikipedia)