Quantitative Assessment of the Chemical Safety of Groundwater Wells in Two Selected Districts of Rwanda

This research was conducted on groundwater wells of Bugesera and Muhanga districts in Rwanda where its physico-chemical parameters were determined as main aim. The study period was between February and May, 2015. A total of 18 water samples were collected from 12 sites. The laboratory experiment focused on the following quantitative determination parameters: Turbidity, pH, Temperature, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Iron, Zinc, Manganese, Nitrate, and Phosphate. Alkalinities (range from 153 to 224 mg/l) in all studied wells were above the standard. Except in one well above the standard, Zinc was detected below the standard in all wells (0.01 up to 0.3 mg/l). Except one well below the range, Iron was found within the normal range in all wells (0.005 – 1.00 mg/l). Manganese was within the normal range in five wells of Bugesera district (0.122 – 0.420 mg/l), whereas below the WHO standard in all wells of Muhanga district (0.003 – 0.087 mg/l). Except one well in Bugesera district all heavy metals in all wells were not exceeded the permissible limits. The samples from Kanogo groundwater well were containing a very high amount of Zinc and Manganese. In some wells detection were found below the standard. TDS (range from 70.5 to 232mg/L), pH (range from5.5 to 6.3) and Electrical conductivity (range from 128 to 335 μs/cm) values in all studied wells were lower than standards provided by Rwanda Bureau of Standards (RBS) and World Health Organization (WHO). This study provides an insight on the quantitative measurements of some chemicals which do have relevance in the use of groundwater wells for domestic consumption. The wells can be utilized with proper management and regular monitoring. However, due to the high amount of heavy metal pollutants in the Kanogo groundwater well of Bugesera district this well should be monitored and treated for the moment. The government and other stakeholders together with the community should seek an alternative safe water supply source. Some preventive measures like planting trees around the well to protect it against entry discharge of residual waste and periodically cleaning of the wells are suggested. It is also important to sensitizing the community so that they can take precautionary measures to the cause; extent and impact of the contamination by these chemicals.