Drinking Water Quality Assessment Using Water Quality Index in Ado-Ekiti and Environs, Nigeria

Abstract

Water quality is a description of chemical, physical and biological characteristics of water in connection with intended use(s) and a set of standards. The quality of water sources has been deteriorated due to point source and non-point source pollution. Therefore, the water quality of any specific source can be investigated using physical, chemical and/or microbiological parameters. One of the most effective tools in communicating information on the quality of water is by using the term water quality index (WQI), which is a rating, reflecting the composite influence of different water quality parameters. WQI provides a single number that expresses the overall water quality at a certain location and time based on several water quality parameters. Hence, this study aimed to assess the quality  of  drinking  water  sources  in  Ado-Ekiti  and  environs,  Nigeria,  using Water Quality Index (WQI). This study was carried out using experimental study design at the Department of Microbiology, Ekiti State University, Ado-Ekiti, Ekiti State, Nigeria, between January 2014 and August 2014. Among several formulated water quality indices, the study adopted the  Weighted  Arithmetic  Water  Quality  Index  (WAWQI) method,  which  classifies water  quality  according  to  the  degree  of  purity. The  WAWQI  was determined on the basis of various physico-chemical parameters which included pH, total dissolved solids,  turbidity,  total  hardness,  calcium,  magnesium,  sulphate,  chloride  and  nitrate.  The parameters were determined using standard methods. The results of the study showed that the  mean  values  of  the  physico-chemical  parameters  of  majority  of  the samples  fell  below  the  WHO  maximum  permissible  limits  while  others  were  above  WHO specifications.  The  calculated  WAWQI  revealed  the  water  quality  level  of  the  different  water sources as follows; 54.16, 65.12, 67.46, 56.29, 46.08  and 49.59 for borehole, stream, pipe-borne, well, spring and packaged water samples, respectively. This result is an  indication  that  the  analyzed  water samples  from  different  sources were of poor water quality with the exception of spring and packaged water samples which are of good  quality in terms of physico-chemical qualities and thus safe for human consumption.