Groundwater Development for Potable Water Supply in Sokoto State, Nigeria: Hydrogeological Potential, Water Quality Assessment, and Sustainability Challenges

Abstract

Groundwater constitutes the primary source of domestic water supply in semi-arid northern Nigeria, yet its suitability for potable use remains insufficiently documented in many rapidly growing urban centres. This study assessed groundwater development for potable water supply in selected neighbourhoods of Sokoto metropolis, Nigeria, including Dambua Area, Arkilla, Gidan Dare, Mana, Runjin Sambo, and Tudun Wada. The study adopted a field-based hydrogeological and water quality assessment design in which groundwater potential was investigated using Vertical Electrical Sounding and borehole data analysis, while water quality was evaluated through physicochemical and microbiological laboratory testing of groundwater samples. Water Quality Index (WQI), statistical analysis, and GIS mapping were applied to determine spatial suitability for drinking purposes. The findings revealed that aquifer systems within the Gwandu Formation show moderate productivity, with borehole yields ranging from 1.2–3.8 L/s and aquifer depths of 18–52 m, indicating adequate groundwater availability for domestic supply. Groundwater quality analysis indicated neutral to slightly alkaline pH but elevated electrical conductivity and total dissolved solids in some locations, reflecting increased mineralisation, while groundwater hardness was widespread with calcium and magnesium concentrations exceeding recommended limits in several samples. Fluoride concentrations exceeded WHO guidelines in parts of Tudun Wada and Dambua, indicating potential long-term public health risks, and iron concentrations surpassed permissible limits in some locations, affecting aesthetic water quality. Microbial contamination, including total coliform and E. coli, was detected in shallow groundwater sources, particularly in Gidan Dare and Mana. Water Quality Index results further revealed that only about one-third of groundwater sources are suitable for direct consumption, while the majority require treatment before use. In addition, increasing borehole drilling, poor sanitation practices, and the absence of groundwater monitoring were identified as major sustainability concerns. The study concludes that although groundwater resources in Sokoto metropolis are adequate to support potable water supply, water quality challenges and sustainability risks require urgent management interventions, and it recommends strengthening groundwater monitoring, regulation, treatment, and protection strategies to ensure safe and sustainable drinking water supply in semi-arid urban environments.