CHAPTER ONE INTRODUCTION 1.1 Background
Water pollution is a large set of undesirable effects upon water bodies such as lakes, rivers, oceans and groundwater that caused by human activities. This matter requires urgent attention, since water is scarce and such an important resource needs detailed scientific research all over the world in order to sustain and protect the water resource from pollution and for its wise utilization. However, no water in nature is absolutely clean. Even as it rains, the precipitation is interact with solid dissolved salts and aerosols in the air prior to reaching the ground, running on the surface and finally percolating through the different geological formations. The major sources of water pollution can be classified as municipal, industrial, and agricultural and there are also other sources of water pollution like petroleum, radioactive substances and heat.
In our country, Ethiopia is also facing the problem of groundwater water quality degradation. There are indicators that the groundwater system has started being polluted in some big cities. According to Taye Alemayehu (1988) and Tamiru Alemayehu (2004) indicated the pollution of groundwater in Dire Dawa and Addis Ababa; on the other hand, the amount of pollution is commonly not large excluding the surface waters of Addis Ababa and groundwater of Dire Dawa city where the problem is at its climax