Human
In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. About 36 million humans die every year from causes directly or indirectly related to starvation. Childhood malnutrition is also common and contributes to the global burden of disease. However global food distribution is not even, and obesity among some human populations has increased rapidly, leading to health complications and increased mortality in some developed, and a few developing countries. Worldwide over one billion people are obese, while in the United States 35% of people are obese, leading to this being described as an "obesity epidemic." Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by an energy-dense diet.
Drinking water quality in the United States
The EPA defines a public water system (PWS) as an entity that provides water for human consumption to at least 25 people (or at least 15 connections) for at least 60 days a year. There are three types of public water system: community systems (like cities or trailer parks); non-transient, non-community systems (like factories or schools with their own water source); and transient non-community systems (like rural restaurants or camps).