CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Water is essential to all forms of life and make up 50-97% by weight of all plants and animal and about 70% of human body (Allan, 1995). Water is also a vital resource for agriculture, manufacturing, transportation. Despite its importance, water is the most poorly managed resource in the world (Chutter, 1998). The public health significance of water cannot be over emphasized. Many infectious diseases are transmitted by water through the fecal oral route. Diseases contacted through drinking water kills about 5million people annually and make 1/6th of the world population sickness (WHO, 2004). Water is vital for the existence of life and its importance in our daily life makes it imperative that thorough microbial, physico-chemical and heavy metal examination of water should be concluded on water used for various purposes to reduce the risks of water borne diseases emanation from such water. Portable water is the water that is free from disease–producing micro-organisms chemical substances that are dangerous to health (laminkera, 1999). In Nigeria, majority of the in the rural and urban area do not have access to portable water and therefore depend on well, stream and river water for domestic use. The bacterial and heavy metal content of well water in Nigeria have been reported to be unsatisfactory; with coliform count exceeding the recommendation by WHO (Edema et al; 2001). Water is the second important resource to human life after air. Man can survive longer without food than without water. Water is an important constituent of biotic community, it occurs naturally on land, underground, in the atmosphere and biomass (Narayanan, 2007). Water pollution should be a concern to every citizen because water accounts for about 70% of the weight of a human body, out of the estimated.
1,011 million km3 of the total water present on 400m3 is available for drinking, agricultural purposes, domestic and industrial uses. The rest of the water is locked up in ocean of salt underground.
These qualities of water and its effect are characterized by its physical, chemical and microbial properties (Narayanan, 2007).
The problem associated with chemical constituents of drinking water arises primarily from their ability to cause adverse health effects after prolonged period of exposure of a particular contaminant that have cumulative toxic properties such as heavy metals and substances that are carcinogenic (Uduma ,2014).
Heavy metals are chemical elements with a specific gravity (S.G) at least 5 times that of water. The specific gravity of water is I at 4oC. Some well known toxic metals with a specific gravity of 5 or more than that of water are cadmium
 (8.65), iron (7.9) Lead (11.34) and mercury (13.546), (Lide, 1992).
Heavy metals are produced from varieties of natural and anthropogenic (man-made activities like mining, disposal of effluents from industries and indiscriminate use of fertilizers and pesticides in cultivation (Amman et al, 2002).
Investigation of the spatial distribution of levels of arsenic, lead and cadmium in Rivers, in kumasi (Ghana) revealed that most of the aquatic life have gone extinct due to the toxicity of the heaving metal to the aquatic organisms in the water (arpong et al; 2009).
In aquatic ecosystem, heavy metal pollution can result from atmosphere deposition of geological weathering or through the discharge of waster. Metals like CU, Fe, Mn, Ni and Zn are essential micronutrients for life processes in plants and micro organisms while other many metals like Cd, Cr and pb have no known physiological activity, but have been proved to be detrimental beyond certain levels (Marschner, 1995)