Sewage and waste water are some of the other problems which lead to water pollution or contamination. The population is growing around the world at an alarming rate. There are many people in a small area which only leads to the increase of waste including sewage, garbage, spilling of fuels and oils into the ground and then into the water supply. In the developing countries or modern countries, sewage water is drained off into the rivers without proper treatment or if treated done in a very poor manners. This slows down the process of diluting the waste water and therefore it flows directly to the rivers, lakes and oceans; then it stagnate the water. In addition many people in the cities do not want to take the time or purchase proper items for disposing of waste material and they just dump it wherever they can. Much research has been done and they have found out that sewage contains many kinds of chemicals, from medicine or prescription drugs to paper and plastic; and when someone is sick the sewage carries these viruses into the environment and water systems, such as cholera and typhoid.