Available online at www.pelagiaresearchlibrary.com Pelagia Research Library Advances in Applied Science Research, 2014, 5(6):194-197 ISSN: 0976-8610 CODEN (USA): AASRFC 194 Pelagia Research Library Bacteriological evaluation of well water in Zaria Metroplis Sule A. M., Hammuel C., Raplong H. H., Idio U. I., Abe A. S., Mohammed H. A. and Otori M. O. Environmental Technology Division, National Research Institute for chemical technology, (NARICT), Zaria, Nigeria ______________________________________________________________________________________________ ABSTRACT This study examined the bacteriological quality of hand-dug well water from five selected areas in Zaria, Nigeria considering the popularity of hand-dug well water as a source of domestic water supply in most homes across the metropolis. The total heterotrophic bacterial (THB) counts of well water samples obtained during the dry season ranged from 1.4 × 10 3 to 2.7 × 10 4 CFU per ml while the THB of well water samples obtained during the rainy season ranged from 3.1 × 10 3 to 1.1 × 10 5 CFU per ml. Coliform count ranged from 350 to 2400 MPN per 100 ml for well water samples obtained during both the wet and dry seasons. The result of the study revealed that water from all the wells under study did not meet minimum permissible THB standard (100CFU/ml) and total coliform standards (10/100 ml) set aside by the world health organization (WHO) and therefore not safe for drinking or for other domestic purposes. Extraction and use of such water without some forms of physical and chemical treatment poses serious risk to public health. It was also discovered that the level of contamination was higher in rainy season when compared to dry season, a wide spatial variation was also observed. Keywords: Bacteriological quality, well water and permissible standard, contamination, public health. _____________________________________________________________________________________________ INTRODUCTION In most developing countries (including Nigeria), access to potable water has become a mirage and exploitation of groundwater through the construction of hand-dug wells is a major source of drinking water for majority of the populace [1]. Despite the considerable investments of Nigerian government in water supply programme, over 52% of its population has no access to potable water [2]. Water covers 70.9% of the earth's surface and is vital for all known forms of life [3]. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation.Wells are categorized based on the nature of construction: open dug wells are generally considered the worst type of groundwater sources in terms of faecal contamination and bacteriological analysis [4]. Dug wells with windlass or hand pumped or mechanically pumped well are generally regarded to be less prone to contamination [5]. [6] assert that open or poorly covered well heads pose the commonest risk to well-water quality; the possibility of the water being contaminated is further increased by the use of inappropriate water-lifting devices by consumers. The commonest physical defects leading to faecal contamination of dug wells are associated with damage to, or lack of, a concrete plinth, and with breaks in the parapet wall and in the drainage channel [6]. The most serious source of pollution of well water is contamination by human waste from latrines and septic tanks resulting in increased levels of microorganisms, including pathogens [5]. The public health significance of water quality cannot be over emphasized. Many infectious diseases are transmitted by water through the fecal-oral route, also the world health organization WHO, [5] reported that diseases contacted through drinking water kill about 5 million children annually and make 1/6 th of the world population sick. thus this work is aim at investigating well