Assessing Groundwater Quality in Kumasi's Peri-Urban Communities
Beneath the bustling streets and vibrant communities of Kumasi's expanding peri-urban landscape lies an invisible resource that millions depend on daily: groundwater. As Ghana's second-largest city, Kumasi has experienced rapid urbanization and population growth, stretching its water infrastructure to its limits 2 5 .
In areas where piped water from the Ghana Water Company Limited is unreliable or nonexistent, residents have turned to boreholes and hand-dug wells as their primary water source. Yet, this essential resource faces invisible threats from multiple contamination sources that could jeopardize public health. Recent studies have revealed alarming facts about what residents are actually consuming when they draw water from these familiar wells.
This article explores the scientific quest to understand and solve Kumasi's groundwater quality challenges—a story of contamination, innovation, and the search for sustainable solutions.
Multiple factors contribute to the contamination of this vital resource in peri-urban areas
Kumasi lies on geologically diverse terrain characterized by granite, metamorphic rocks, and sedimentary deposits that form the aquifers supplying groundwater to the region. The city's aquifer system is predominantly shallow, consisting of sand with a thickness of approximately 7-10 meters 5 .
These geological formations create what hydrologists call "secondary porosity"—networks of fractures, faults, and shear zones that allow water to flow and be stored within otherwise solid rock 2 .
The climate of Kumasi features a wet sub-equatorial pattern with two peak rainfall periods (June and September) and an average annual rainfall of 1400 mm 2 5 . This rainfall naturally replenishes groundwater supplies through infiltration.
However, rapid urbanization has dramatically altered this natural recharge process, with increasing paved surfaces reducing water infiltration while growing demand places additional pressure on the limited resource.
In peri-urban Kumasi, where formal sanitation infrastructure is often lacking, multiple contamination sources threaten groundwater quality. Scientific investigations have identified several primary pathways through which pollutants enter the aquifer system:
Pit latrines and septic tanks represent one of the most significant contamination sources. As settlement patterns become denser without corresponding sewage infrastructure, the cumulative effect creates widespread microbial and nutrient contamination .
The Oti landfill site has emerged as a major concern. Studies found that mean concentrations of lead (Pb), iron (Fe), cadmium (Cd), and chromium (Cr) exceeded WHO acceptable limits for drinking water 6 . Without proper lining, the landfill acts as a continuous pollution source.
Improper waste disposal and domestic activities contribute to the problem, with improperly maintained water storage tanks becoming breeding grounds for biofilm and microbial growth 5 . Natural weathering of mineral-rich soils also releases elements into groundwater.
| Contaminant Category | Specific Contaminants | Primary Sources | Health Effects |
|---|---|---|---|
| Heavy Metals | Lead (Pb), Chromium (Cr), Cadmium (Cd), Iron (Fe) | Landfill leachate, natural weathering of rocks | Neurological damage, kidney problems, increased cancer risk |
| Microbial Pathogens | E. coli, Total Coliforms | Pit latrines, septic tanks, surface runoff | Diarrheal diseases, typhoid, cholera |
| Nutrients & Chemicals | Nitrates, Nitrites, Phosphates | Agricultural runoff, sanitation systems | Methemoglobinemia ("blue baby syndrome"), cancer risk |
| Physical Parameters | Turbidity, Total Dissolved Solids | Soil erosion, inadequate filtration | Gastrointestinal issues, interference with disinfection |
Testing innovative solutions to address both water quantity and quality challenges
Faced with declining groundwater levels and quality concerns, researchers conducted a groundbreaking study to test a potential solution: Managed Aquifer Recharge (MAR) using Rooftop Rainwater Harvesting Systems (RRWHS). This innovative approach represents a paradigm shift from simply documenting problems to actively testing solutions 2 .
The study was conducted in Akyeremade and Kwanwoma—two peri-urban communities at the fringes of Kumasi where residents depend solely on groundwater from shallow wells and boreholes. These communities experience the familiar pattern of wells drying up during dry seasons despite having adequate rainfall during rainy seasons.
The research team selected six hand-dug wells for monitoring:
Over 12 months, researchers continuously monitored groundwater levels and collected 50 water samples for analysis to track changes resulting from the recharge intervention.
Researchers identified houses with hand-dug wells that experienced seasonal water level decline. Selection criteria included suitable roof designs, presence of hand-dug wells, homeowner confirmation of low water levels, and willingness to participate.
Rooftop rainwater harvesting systems were installed on four houses, designed to channel rainwater by gravity directly into the wells. The systems included first-flush diverters to exclude the initial rainfall that typically carries the most contaminants from roof surfaces.
Researchers used Van Essen Conductivity (CTD) divers to continuously monitor groundwater levels. Rainfall data was obtained from the Trans-African Hydro-Meteorological Observatory (TAHMO) to correlate with groundwater responses.
The team collected and analyzed water samples for physicochemical parameters and microbial contamination throughout the study period, allowing them to track any changes in water quality resulting from the recharge intervention.
Using the Water Table Fluctuation method, researchers quantified how much additional recharge occurred in the MAR-equipped wells compared to the control wells.
| Research Tool | Function/Purpose | Significance in the Study |
|---|---|---|
| Van Essen CTD Divers | Continuous monitoring of groundwater levels | Provided high-resolution data on how water levels responded to rainfall and recharge |
| First-Flush Diverter | Excluded initial rainfall containing roof contaminants | Reduced the risk of adding contaminated water to wells |
| Water Table Fluctuation Method | Calculated actual groundwater recharge rates | Quantified the effectiveness of the MAR intervention |
| Physicochemical Analysis | Assessed water quality parameters | Monitored potential changes in water quality due to MAR |
| Microbial Assessment | Detected bacterial contamination, including E. coli | Evaluated health safety of recharged groundwater |
The findings from this year-long investigation revealed both the promise and complexities of the MAR approach:
Rainfall harvested and infiltrated into the aquifer
Higher recharge in MAR wells compared to controls
Median recharge in MAR wells
| Parameter | MAR Wells (with RRWHS) | Control Wells (without RRWHS) | Significance |
|---|---|---|---|
| Median Recharge | 231 mm | 97 mm | MAR wells recharged 3x more effectively |
| Response to Rainfall | Rapid, consistent response | Gradual, inconsistent response | MAR provides more reliable recharge |
| Nitrate Levels | Reduced concentration due to dilution | Variable, dependent on natural conditions | Potential water quality improvement |
| Turbidity | Increased immediately after rainfall | Less affected by individual rain events | Requires management to maintain quality |
| Seasonal Performance | Consistent recharge during rains | Significant dry season decline | MAR helps address seasonal water shortages |
Essential methods and equipment for groundwater assessment
These automated sensors provide continuous, high-frequency monitoring of conductivity, temperature, and water depth—fundamental parameters for understanding groundwater dynamics and identifying contamination events 2 .
Used to detect and quantify fecal indicator bacteria like E. coli and total coliforms, these kits help researchers assess the microbiological safety of groundwater and identify sewage contamination 5 .
These sophisticated laboratory instruments enable precise measurement of heavy metal concentrations at very low levels, essential for detecting toxic metals like lead, cadmium, and chromium 6 .
GIS mapping and spatial analysis techniques help visualize contamination patterns, identify hotspots, and understand the relationship between land use and groundwater quality across the study area.
Connecting scientific findings to health risks and sustainable management strategies
The scientific findings from Kumasi take on greater urgency when examined alongside health risk assessments. Research has documented hazardous levels of copper and lead ingestion from groundwater sources in areas like Appiadu, where metal concentrations exceeded WHO limits 5 .
Studies in Ghana's Eastern Region found that approximately:
The most vulnerable districts included Atiwa East, Fanteakwa North, Achiase, Birim South, Akwapim, Suhum, and Ayensuano—highlighting the need for targeted interventions in high-risk areas.
The challenges facing Kumasi's groundwater are significant but not insurmountable. Scientific evidence points to several promising strategies:
The success of the MAR-RRWHS experiment suggests that scaling up this approach could help address both water quantity and quality challenges in peri-urban areas 2 .
The World Health Organization promotes WSPs as comprehensive risk assessment and management tools that can be adapted to peri-urban groundwater sources, though implementation challenges remain .
Emerging governance frameworks that complement traditional water management with more flexible, adaptive approaches show promise for addressing complex groundwater challenges .
Simple interventions like educating households on proper well maintenance, regular cleaning of water storage tanks, and safe water handling practices can reduce contamination risks at the point of use 5 .
The story of groundwater in Kumasi's peri-urban communities is still being written. Scientific investigations have revealed the sobering reality of an invisible crisis—contaminated wells, depleted aquifers, and associated health risks. Yet research has also illuminated pathways forward, from innovative recharge techniques like MAR-RRWHS to improved governance frameworks.
The work of scientists, community members, and policymakers will determine whether this essential resource becomes a story of sustainable coexistence or a cautionary tale.
What remains clear is that ensuring safe groundwater for Kumasi's growing population will require continued scientific inquiry, community engagement, and political will. As one researcher involved in the MAR study noted, the goal is not just to understand the aquifer system, but to work with communities to develop practical solutions that ensure safe, reliable water for all—making the invisible visible once again.