ABSTRACT

Bacteriological and physicochemical properties of drinking water (tap, well and borehole) in Sokoto metropolis were investigated to determine the level of contamination and the persistence of target organisms. A total of 270 samples comprising of 90 well water samples, 90 tap water samples and 90 boreholes water samples were obtained from some parts of Sokoto metropolis and analyzed using standard procedures. Total coliform count, heterotrophic plate count, physico-chemical properties feacal-coliform count and the presence of Escherichia coli, Enterobacter species, Bacillus subtilis, Shigella species, Salmonella species, Citrobacter species, Staphylococcu saureus and Bacillus cereus were determined. Biochemical identification showed that out of the 108 confirmed Escherichia coli isolates, 51(47%) were from well water and of the 42 Enterobacter species recovered 19 (45%) were from well water while5 (42%) out of 12 Salmonella species were also recovered from well water. The tap water had 26 (24%) Escherichia coli, 13(30%) Enterobacter, 3 (25%) Salmonella species, 5(71%) Bacillus species and other unidentified organisms while in contrast, borehole water had 31 (29%) Eschericia coli, 10 (24%) Enterobacter, 4 (33%) Salmonella species, 2 (26%) Bacillus and other unidentified organisms. No Vibrio species were isolated in all cases. The molecular analysis showed that out of the 79 isolates identified from biochemical analysis, 40 isolates were further subjected to molecular analysis using microgen GN-ID System (kit method).There were 13 (33%) inactive Eechericia coli, 5 (13%) active Eschericia coli and 10 (25%) were other organisms, while the remaining 12(30%) were not identified. The physicochemical properties show that the highest pH was in borehole water sample (6.73) while the lowest was in well water samples (5.7). The highest Electrical conductivity was in tap water samples (142.67 µs/cm), while the lowest was in well (5.8 µs/cm). The highest value of dissolved oxygen was in borehole water samples (8.83 mg/l) and the lowest was found in tap water samples (3.57 mg/l). The highest BOD was in well water samples (15.57 mg/l) while the lowest was in tap water samples (7.73). Therefore, adequate treatment of all waters and public health education are highly recommended.

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CHAPTER ONE

1.0                                                                       INTRODUCTION

1.1         Background to the study

Water is a common chemical entity that is essential for the survival of all known forms of life (Solanki et al., 2012). The qualities of drinking water are powerful environmental determinants of health (WHO, 2010). Water plays an indispensable role in sustenance of life and it is a key pillar of health determinant, since 80% of diseases in developing countries are due to lack of good quality water (Chessbrough, 2006). Drinking water quality management has been a key pillar of primary prevention of infections for over one and half centuries and it continues to be the foundation for the prevention and control of water-borne diseases (WHO, 2010). Water is the most abundant natural resource; although, it is not readily available in the form required by man (Obi and Okocha, 2007). The provision of good quality household drinking water is often regarded as an important means of improving health (Essien and Olisah, 2010). Good quality water must be colourless, odourless, tasteless and free from faecal pollution (Ezeugwunne et al., 2009; Omalu et al., 2010). Water plays an important role in the prevention of diseases; taking eight glasses of water daily minimizes the tendency of colon cancer by 45% and bladder cancer by 50% as well as reducing the risk of other cancers (Oparaocha et al., 2010).

In many developing countries, availability of good drinking water is a major and critical problem and· it is a matter of great concern to our societies depending on non-public water system (Umezuruike et al., 2009). Increase in human population poses a great pressure on provision of safe drinking water especially in developing countries

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(Umezuruike et al.,2009). Consequently, water-borne diseases such as cholera and typhoid often have their outbreak especially during dry season (Banu and Menakuru, 2010). Contaminated water is a global public health threat placing people at a risk of a host of diarrhoeal and other illnesses (Umezuruike et al., 2009). Although water can contain undesirable chemicals (from natural sources), the major risk to human health is faecal contamination of water supplies. Serious ill health can be caused by water contaminated with faeces being passed or washed into rivers, streams, pools or being allowed to seep into wells or boreholes (Cheesbrough, 2006).

Water of good drinking quality is of basic importance to human physiology and man's continued existence depends very much on its good quality and availability (Umezuruike et al., 2009). The provision of potable water to the rural and urban populations is necessary to prevent health hazards. Before water can be described as potable, it has to comply with certain physical, chemical and microbiological standards, which are designed to ensure that the water is palatable and safe for drinking (Umezuruike et al.,2009). Potable water is defined as water that is free from diseases-producing microorganisms and chemical substances deleterious to health (Umezuruike et al.,2009). Water can be obtained from a number of sources, among which are streams, lakes, rivers, ponds, rain, springs, taps and wells (Umezuruike et al., 2009). Unfortunately, clean, pure and safe water only exists briefly in nature and is immediately polluted by prevailing environmental factors and other human activities. Water from most sources is therefore unfit for immediate consumption without some sort of treatment (Umezuruike et al.,2009).

Water in nature is seldom totally pure. Rainfall is for example, is contaminated as it falls to earth, as a result of combustion of fossil fuel which add sulphur compound

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responsible for acid rain. Water that moves below the ground's surface undergoes filtration that removes most organisms(Tortora et al., 2002). For this reason, water from springs and deep wells are generally of good quality. Contaminants ingested into water supply cause many diseases, such as typhoid fever, dysentery, cholera and gastro entritis. Examples of such pathogens are Salmonella species, Shigella species, Vibrio cholerae and E. coli (Tortora et al., 2002; Oladipo et al., 2009).Industrial and agricultural chemicals leached from the land, enter water ina great amount and they could be resistant to biodegradation. Apart from this, rural water often has excessive amounts of nitrite from microbial action on agricultural fertilizers (Tortora et al., 2002; Oladipo et al., 2009).

To attain a safe water supply to various communities, an understanding of water that is bacteriologically and chemically certified is therefore imperative. Above all, to ensure that the bacteriological quality of drinking water is safe for human consumption, the Nigeria based National Agency for Food and Drugs Administration Control (NAFDAC) in association with the World Health Organization (WHO), recommended that potable water should not contain any microorganism that is known to be pathogenic and the coliform number per 100 ml of water must be zero. However, it may contain three coliforms per 100 ml of water sample in occasional samples (Oladipo et al., 2009). The bacteriological quality of public drinking water is of paramount importance and its monitoring must be given highest priority. This is so because studies (Oparaocha et al., 2010) have attributed several disease outbreaks to untreated or poorly treated water containing bacterial pathogens that have been isolated from public drinking water.

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1.1         Justification for the Study

The bacteriological quality of drinking water is a concern to consumers, water suppliers, regulators and public health authorities. The potential of drinking water to transmit microbial pathogens to great number of people causing subsequent illness is well documented in many countries at all levels of economic development. The number of outbreaks that has been reported throughout the world demonstrates that transmission of pathogens by drinking water remains a significant cause of illnesses. However, estimate of illness based solely on detected outbreaks is likely to underestimate the problem. A significant proportion of water-borne illnesses are likely to go undetected by the communicable disease surveillance reporting systems. Therefore, it is of paramount importance to assess the microbiological standard of public water in order to improve sanitation and reduce the incidence of diseases transmission.

1.2         Aim and Objectives of the Study

The aim of this study was to determine the bacteriological quality of public drinking water (borehole, well and taps) and characterize (biochemical and molecular) pathogens isolated these from Sokoto metropolis. Therefore, it is made up of the following specific objectives

i.               to determine the physicochemical properties of the drinking water samples;

ii.            to enumerate aerobic and mesophilic faecal and non faecal coliform;

iii.           To isolate and comparethe bacteriological standard, and to determine the total coliform count of public drinking water in Sokoto metropolis with WHO, NAFDAC and Nigerian Standard for Drinking Water Quality (NSDWQ) standards.