ABSTRACT
This study evaluated the ground water quality of the Okhunmwun Community in Ovia Northeast local government, Edo state in Geospatial Information System (GIS) environment. Groundwater plays a vital role in sustaining communities so water quality evaluation is very important to ensure a regular supply of potable water. The study was conducted to determine the necessity of routinely checking the quality of the groundwater and treating it before consumption. Six water samples, two from each of the three locations (A, B, and C), one from the tap and one from the borehole, were taken. The samples were taken to the Marlet Environmental Research laboratory in Benin City where the physical, chemical and microbial parameters were examined and compared to the World Health Organization's (WHO), Nigerian Standard for Drinking Water Quality (NSDWQ) and Nigerian Agency for Food and Drugs Administration and Control (NAFDAC) standards for drinking water quality. The physical parameters includes; Turbidity, Colour, Total Dissolved Solids(TDS), Chemical Parameters; pH, Alkalinity, Chloride, Sulphate, Nitrate, Iron and Manganese, Microbial parameters: Bacteria Isolates, Total coliform count. The water quality index (WQI) was then calculated for each sample and a GIS database was created using the ArcGIS software. The physical and chemical characteristics of the laboratory test results from Marlet Laboratory, were all in compliance with the WHO, NSDWQ, and NAFDAC requirements for drinking water quality except for pH value. The pH value obtained fell into the range of 6.0 – 6.2 which is below the WHO, NSDWQ and NAFDAC standard of 6.5 – 8.5. The low pH value indicates that the water is slightly acidic and can be increased by using soda ash to treat the water. For the microbial analysis, it was found that there were no bacteria found in the water. The result of the WQI for all the six samples fell into the range of excellent and good water quality meeting the WHO standard for drinking water quality. For borehole water samples, locations A, B and C results were gotten as 90.17%, 90.44% and 90.0% respectively. For tap water samples, location A, B and C results were gotten as 87.80%, 88.81% and 87.84% respectively. A simple query was executed in the GIS database to determine the locations with the best water sample and locations with pH values that fell below WHO standards. Results displayed that borehole water samples from all the locations are of best quality falling into the excellent water standard of 90-100% set by WHO and pH values for all locations were below the WHO standard. From all the results obtained, the water samples meet the necessary criteria for drinking water quality by the regulatory bodies’ standard but the pH needs to be increased by applying soda ash (Sodium carbonate) or limestone (Calcium carbonate) to the water. Regular cleaning and monitoring of the storage tanks for leaks and replacement of old pipes should be done to maintain the quality of water getting to the consumers.
