Evaluating Physico-Chemical Parameters in Zanzibar North Region Water Wells

This study was aimed at assessing the levels of turbidity, salinity, Dissolved Oxygen (D.O), pH, Electrical Conductivity (EC), temperature and Total Dissolved Solids (TDS) using in situ YSI ProDSS Multi-Parameters Water Quality Meter (Multi-Sonde). In May 2018, twenty five groundwater samples were collected from open hand dug wells, and closed hand dug wells in different sites of North A and North B districts in North Region of Zanzibar. The ranges of TDS, EC, and salinity were; 43 - 611 mg/L; 121.20 - 2176 µS/cm; 0.05 - 1.03 ppt respectively. 80.0 %, 12% and 96% of the water samples respectively had TDS, EC and Salinity values which fall under excellent category. Whereby, 8.0% of water samples had unacceptable EC levels these sources are Kitope Mwembemajogoo (EC = 2176 µS/cm), Mkokotoni (EC = 1215 µS/cm) and Kiwengwa Kumbaurembo (EC = 1806 µS/cm). The ranges of DO, Turbidity, Temperature and pH in analyzed water samples were; 1.74 - 8.43 mg/L; 0.56 - 34.4 NTU; 25.40 - 32.0 ° C and 5.27 - 8.60 respectively. Only 16% of the water samples had DO values within the acceptable range. For the parameter of turbidity, only, 40% of water samples had turbidity values within the acceptable range. Lastly, with respect to pH 56% of the water samples had pH values which are within the acceptable range. Kitope water source was more alkaline (pH = 8.60). It is extremely worthy to mention that the pH at Mahonda region was comparatively low, a typical example is Mahonda Mkataleni water source (pH = 5.27). The possible reason for the observed low values in pH in this region could be attributed by seepage of some chemicals from Mahonda Sugar Industry into ground water reservoirs. There was a strong positive correlation shown by some parameters including EC and TDS (r2 = 0.874), EC and salinity (r2 = 0.99). In conclusion, some of the water samples had values that deviated from the standard international permissible values of WHO. Therefore, regarding to the analyzed parameters there is a strong need to monitor on daily basis, the quality of the groundwater sources as ascertain their suitability for human consumption and even other living organisms.