For the price of the Iraq War, we could've desalinized enough seawater to provide all Africans with safe drinking water for the next 7,992 years.
Currently, the majority of the 922 million people in Africa do not have safe drinking water. Drinking 2 L of water per day is sufficient to replenish bodily fluids. So providing Africans with their annual intake of water would require 673 billion liters.
Singaporean desalinization technologies produce 1 cubic meter of fresh water for $0.49. At this price, supplying all Africans with clean drinking water until the year 10,000 AD would cost $2.63 trillion, which is less than Joseph Stiglitz and Linda Bilmes' estimate of $3 trillion for the cost of the Iraq War.