text: Because they dont have water filters to purify thier water. All thier waste gets dumped into local rivers, streams, or lakes, and without a pump or purification system they are forced to drink the water to survive even though the water is so contaminated with parasites, fungus, and hundreds of diseases. The contaminated water, in most 3rd world countries, also makes it almost impossible to find any food or animals around the water sources. So even if the people didnt drink the water, they would still be influenced due to the food and animals they eat.