An assessment of the potability of groundwater from boreholes based on microbial quality and physical properties: case of Buea and Tiko Subdivisions, South West Region of Cameroon

Abstract

Groundwater from boreholes, though generally considered as potable water, is vulnerable to both microbial pollution and unsuitable physical characteristics. An assessment of the microbial quality and the physical properties of groundwater from boreholes was accordingly carried out in Buea and Tiko subdivisions to determine these parameters. In particular, the presence of coliform bacteria and an eventual isolation of E. coli and Salmonella spp which are faecal indicator organisms were carried out. A total of 46 samples were collected from 29 randomly selected boreholes and their physical parameters (temperature, pH, EC, TDS and turbidity), and microbial content analyzed. Physical parameters were measured in-situ using portable field devices while total coliform count and isolation of faecal coliforms (E. coli and Salmonella spp) were determined using standard microbiological methods with reagents, Violet Red Bile Agar, Mackonkey Agar and Salmonella Shigella Agar respectively. The results indicated that the physical characteristics of the water (pH range 4.9-8.4; EC range 90µS/cm-233µS/cm; TDS range 61 mg/L-1630 mg/L; Turbidity range 0.44NTU-59.80NTU) were within WHO guidelines for potability except for the turbidity with barely two samples that fell within the acceptable range of 1.5NTU. Total coliform counts ranged from 1x100CFU/ml to 3x103CFU/ml and 72.41% of the samples exceeded the WHO recommended 0.0 CFU/100 ml. E. coli was isolated in 76.47 % while Salmonella spp was isolated in 82.35% of the samples. This pioneer study on groundwater quality from boreholes in the study area reveals that the water is vulnerable to bacteriological pollution and therefore not potable. This necessitates awareness creation of the community on the regular disinfection of groundwater from boreholes. RESUMELes eaux souterraines des forages, bien que generalement considerees comme de l’eau potable, sont vulnerables a la fois a la pollution microbienne et a des caracteristiques physiques inappropriees. Une evaluation de la qualite microbienne et des proprietes physiques des eaux souterraines des forages a donc ete realisee dans les departements de Buea et Tiko pour determiner ces parametres. En particulier, la presence de bacteries coliformes et un eventuel isolement d’E. Coli et l’espece de Salmonella qui sont des organismes indicateurs de contamination fecale ont ete realises. Au total, 46 echantillons ont ete preleves dans 29 forages selectionnes au hasard et leurs parametres physiques (temperature, pH, CE, TDS et turbidite) et leur contenu microbien ont ete analyses. Les parametres physiques ont ete mesures sur place a l’aide d’appareils de terrain portables, tandis que le nombre total de coliformes et l’isolement des coliformes fecaux (E. coli et Salmonella spp) ont ete determines a l’aide de methodes microbiologiques standard avec des reactifs, la gelose violette rouge, la gelose Mackonkey et la gelose Salmonella Shigella respectivement. Les resultats ont indique que les caracteristiques physiques de l’eau (plage de pH 4,9- 8,4; plage CE 90µS/cm-2330µS/cm; plage TDS 61 mg/L-1630 mg/L; plage de turbidite 0,44NTU- 59.80NTU) etaient conformes au directives de l’OMS pour la potabilite. Seul, la turbidite avait a peine deux echantillons qui se situaient dans la plage acceptable de 1,5NTU. Le nombre total de coliformes variait de 1x100 CFU/ml a 3x103 CFU/ml et 72,41% des echantillons depassaient les 0,0 CFU/100 ml recommandes par l’OMS. E. coli a ete isole dans 76,47% tandis que l’espece Salmonella a ete isolee dans 82,35% des echantillons. Cette etude pionniere sur la qualite des eaux souterraines des forages dans la zone d’etude revele que l’eau est vulnerable a la pollution bacteriologique et donc non potable. Cela necessite une prise de conscience de la communaute sur la desinfection reguliere des eaux souterraines des forages.