Assessment of Groundwater Quality in Rural and Urbanized Areas of Maiduguri, Borno State, Nigeria

In Maiduguri, northeastern Nigeria, groundwater serves as the primary water source due to limited surface water access and infrastructure challenges. However, its quality remains inadequately monitored. This study assessed the chemical and microbial quality of groundwater from 21 locations across urban and rural areas, including boreholes, Alau Dam, and a treated water control. Physicochemical analysis revealed variable water quality, with 33% of samples classified as sodium-chloride (Na-Cl) and 67% as calcium-chloride (Ca-Cl) types. Elevated sodium levels were recorded in several rural boreholes, with 25% of samples exceeding safe Sodium Adsorption Ratio (SAR) thresholds for irrigation. Other indices such as Soluble Sodium Percentage (SSP) and Magnesium Adsorption Ratio (MAR) also indicated potential soil degradation risks. Microbiologically, all samples tested positive for total coliforms, but none contained Escherichia coli, suggesting minimal recent fecal contamination but a need for improved borehole sanitation. Statistical analysis (PCA) indicated differing contamination sources between urban and rural sites, with urban samples showing signs of anthropogenic pollution, while rural samples were more influenced by geological factors. The study concludes that while most groundwater sources are microbiologically safe for now, their chemical composition may limit long-term agricultural use. Regular monitoring, improved borehole design, and public education are recommended to ensure sustainable groundwater use in Maiduguri.