clean drinking water
The water Americans get from their faucets is safe. This water has been treated and purified. At least 20% of the worlds people do not have clean drinking water always available. That's more than 1 billion people. They must drink water from where they can get it. Maybe straight from a river or pond Figure below . Human wastes may be in the water. If that's the case, the water will probably contain pathogens. Pathogens are organisms that cause diseases.