By Dr. M. A. Dan-Hassan
ABSTRACT
Boreholes are among Nigeria’s most important pathways to groundwater, particularly where public water systems are unreliable or absent.
Yet a borehole that produces water is not necessarily a successful water-supply asset.
Failure may occur through unsuccessful drilling, low or declining yield, excessive drawdown, defective construction, pump and electromechanical breakdown, contamination, poor operation and maintenance, or institutional weaknesses.
The implications extend beyond engineering performance. When a protected water point fails, households may shift to less reliable or less safe sources, reducing water availability for hygiene and sanitation and potentially increasing exposure to microbial or chemical hazards.
This article examines borehole failure through an integrated hydrogeological, medical-geology, WASH and public-health lens.
It considers Nigeria’s varied geological settings, the importance of hydrogeological investigation and geophysical siting, drilling and completion quality, borehole development, pump selection, water-quality surveillance, and the role of standards such as NCP 027:2010.
It also explores the pathway from geology and mineral–water interaction to groundwater chemistry, human exposure and health outcomes.
Nigerian case illustrations from Lagos demonstrate why water-quality testing and source protection should be treated as core indicators of borehole success.
The article concludes by proposing a life-cycle asset-management approach in which borehole planning, construction, commissioning, operation, monitoring, rehabilitation and safe decommissioning are treated as one continuous system.
*Keywords: borehole failure; groundwater; Nigeria; medical geology; hydrogeology; WASH; public health; water quality; fluoride; arsenic; groundwater governance.
- Introduction: Beyond the Drilled Hole
Across Nigeria, groundwater development has become an essential component of domestic, institutional, agricultural and emergency water supply.
Boreholes are frequently viewed as relatively direct solutions to water shortages: identify a site, drill to an aquifer, install a pump and deliver water.
The apparent simplicity of this sequence can obscure the complexity of the groundwater system beneath the surface.
A borehole is an engineered access point into a natural geological system. Its performance is controlled by lithology, fractures, weathering, aquifer geometry, recharge, hydraulic connectivity, groundwater chemistry, land use and the quality of construction.
Its service life is then influenced by pumping practice, maintenance, financing, community management and institutional oversight.
The source presentation underpinning this article therefore defines failure broadly: a borehole may be physically functional yet fail as a safe and sustainable water service.
This broader definition matters because the consequences of failure can move rapidly from infrastructure to public health.
Loss of a protected water source can push households toward rivers, shallow wells, water vendors or other unprotected sources.
Reduced water quantity can also compromise handwashing, sanitation and food hygiene. Where replacement groundwater sources have different chemistry, a service failure can also alter patterns of exposure to geogenic contaminants.
- What Constitutes Borehole Failure?
Borehole failure is best understood as a family of failure modes rather than a single event.
The technical framework in the presentation identifies seven broad categories: dry or unsuccessful holes; low-yield boreholes; rapid drawdown or poor recovery; construction failures; pump and electro-mechanical failures; water-quality failures; and management or service failures.
Borehole Failure and Implication Categorisation.
Failure Type: Typical Manifestation Public Health/Service Implication.
Unsuccessful/dry: No economically viable water-bearing zone; Loss of investment; continued water insecurity.
Low yield Discharge: Below design demand ; Insufficient water for domestic and hygiene needs.
Hydraulic performance: Excessive drawdown or slow recovery; Unsustainable abstraction; unreliable supply.
Construction: Casing, screen, gravel pack or seal defect, sand, turbidity, structural failure or contamination pathway.
Pump/electromechanical: Pump, power, controls or rising-main breakdown; service interruption; possible unsafe alternatives.
Water quality : Microbial, chemical or radiological unsuitability; direct exposure risk; treatment/source substitution required.
Management/service: Poor O & M, financing, monitoring or spare parts Recurring breakdown and premature asset failure.
- Nigeria’s Hydrogeological Diversity: No Single Borehole Recipe
Nigeria contains markedly different groundwater environments.
In Basement Complex terrain, groundwater occurrence is commonly controlled by weathered zones, joints and fractures.
In sedimentary basins, aquifer geometry, lithology, confinement and structural setting may produce multilayered or laterally variable groundwater systems. Alluvial and coastal deposits can be productive but may also be vulnerable to shallow contamination or salinity.
The presentation emphasises that one drilling method, depth rule or yield expectation cannot be universally applied across the country.
This variability is a fundamental reason why hydrogeological investigation must precede drilling.
The question is not simply whether groundwater exists, but where it occurs, how much can be abstracted sustainably, how it is replenished, what its hydraulic connections are, and what its natural and anthropogenic chemistry may be.
- Geological and Hydrogeological Causes of Failure:
Many borehole failures begin with an incomplete understanding of the subsurface. A poorly interpreted lithological sequence may cause the drilling team to miss the productive horizon.
Thin saturated intervals or low-permeability formations may provide insufficient transmissivity.
Structural features such as faults, fractures and lineaments can strongly influence yield, but their presence does not automatically mean that they are hydraulically productive.
Hydrogeological failure may also occur after a successful commissioning test. A short-term pumping yield is not synonymous with a sustainable long-term abstraction rate.
If abstraction exceeds recharge or available storage, water levels may decline progressively.
Closely spaced boreholes can interfere with one another, while urbanisation, soil sealing, drought and land-use change can modify recharge.
Seasonal fluctuations may also expose weaknesses that are not evident during a limited pumping test.
- Siting, Geophysics and the Problem of Uncertainty:
Good borehole siting should integrate a desk study of geology, hydrogeology, existing boreholes, water levels and water quality with field reconnaissance, hydrogeological mapping and appropriate geophysical surveys.
The presentation stresses the importance of multiple lines of evidence rather than reliance on a single geophysical anomaly.
Geophysics reduces uncertainty; it does not eliminate it. A conductive anomaly, for example, may represent clay, saline water, weathered material or another geological condition.
The geophysical interpretation must therefore be tested against geological and hydrogeological evidence.
Equally important is the sanitary and land-use context: a technically promising aquifer may be a poor source if the borehole is vulnerable to nearby sanitation, waste disposal, fuel handling or industrial activities.
The professional objective should therefore be to manage uncertainty before drilling rather than discover it after failure.
- Drilling, Completion and Borehole Development:
Construction quality determines whether the borehole becomes a stable hydraulic connection to the aquifer or a persistent source of technical problems.
The presentation identifies unsuitable drilling methods, inadequate diameter, poor casing and screen selection, insufficient or poorly graded gravel pack, inadequate sanitary seals, drilling-fluid invasion, poor development, casing damage and screen blockage among the principal construction risks (Dan-Hassan, 2017).
Borehole development is particularly important. Development removes drilling fluids, fine and unstable particles around the screen.
Inadequate development can produce turbidity, sand pumping, reduced specific capacity and premature pump wear.
Development should therefore be documented, including the method used, duration, discharge and observed changes in water quality and hydraulic performance.
The sanitary seal and surface completion deserve equal attention. A borehole can become a preferential pathway for contamination if the annular seal, wellhead, drainage or casing integrity is defective.
In this sense, good engineering is also preventive public health.
- Pump and Electromechanical Failures:
Not every failed borehole is an aquifer failure. Pump systems can fail because the pump is poorly matched to the dynamic water level and borehole yield, because of incorrect setting, inadequate electrical protection, dry running, voltage fluctuations, solar-system faults, corrosion, scaling, sand ingestion, rising-main leakage or storage-system defects.
Diagnostic clues include a motor that runs without discharge, progressively reduced discharge, unusually high energy consumption and frequent protective trips (Dan-Hasssan, 2017).
Pump selection should therefore be based on the borehole’s actual hydraulic characteristics, including static and dynamic water levels, discharge, total dynamic head and operating regime.
Oversizing can contribute to excessive drawdown, while undersizing may fail to meet demand. Maintenance should focus on trends rather than breakdown events alone.
- When Water Quality Becomes a Borehole Failure:
One of the most important arguments of this article is that water quantity and water quality must be considered together.
The presentation classifies water-quality failure into microbial, geogenic chemical, anthropogenic chemical, radiological and acceptability-related problems.
Microbial contamination may enter through defective sanitary seals, cracked casing, flooding, poor drainage, nearby latrines, septic systems, refuse dumps or animal enclosures.
Geogenic constituents such as fluoride, arsenic, iron and manganese can arise from mineral–water interaction and local geochemical conditions.
Anthropogenic contaminants may include nitrate, hydrocarbons, pesticides, solvents and metals.
Radiological concerns depend strongly on local geology and groundwater geochemistry.
The practical implication is straightforward: water-quality testing should form part of commissioning and ongoing surveillance. A borehole should not be declared successful merely because it meets a yield target.
- Medical Geology: From Rock to Water to Human Health:
Medical geology provides a powerful framework for understanding why groundwater chemistry matters to health.
The conceptual pathway is: geology → geochemistry → groundwater → exposure → health.
Minerals, fractures and sediments influence the chemical environment. Processes such as dissolution, precipitation, adsorption, desorption, redox reactions and residence time influence groundwater chemistry.
The resulting water becomes an exposure medium through drinking, cooking and, in some circumstances, food production.
This framework also prevents simplistic conclusions. The presence of a constituent in water does not automatically establish disease.
Risk depends on concentration, chemical form, route of exposure, dose, duration and characteristics of the exposed population.
Medical geology therefore complements, rather than replaces, epidemiology, toxicology and public-health risk assessment.
- Fluoride: A Classic Geogenic Health Risk:
Fluoride illustrates the dual nature of geological constituents. Fluoride may originate from fluoride-bearing minerals, with dissolved concentrations influenced by water–rock interaction, residence time, pH and other geochemical conditions.
Low or moderate exposure can contribute to dental health, whereas excessive exposure during tooth development can cause dental fluorosis, and long-term high exposure can contribute to skeletal fluorosis.
The natural environment can impact health in a variety of ways (Centeno et al., 2016).
- Microbial Contamination and Sanitary Integrity:
The assumption that groundwater is automatically safe because it is underground is dangerous. Groundwater can be microbiologically contaminated where the wellhead, casing or sanitary seal provides a pathway from the surface.
Flooding and poor drainage can intensify the problem. Repeated contamination after rainfall can be a particularly useful clue to a surface-to-aquifer or wellhead pathway.
Indicators such as E. coli are central to assessing faecal contamination and immediate microbial risk.
However, disinfection should not be used as a substitute for structural correction.
- Borehole Failure and the WASH-Disease Nexus:
The public health consequences of borehole failure often arise indirectly. When a water point breaks, households still need water.
They may switch to surface water, shallow wells or other unprotected sources.
Water may be collected from greater distances, transported and stored under conditions that increase contamination risks.
Reduced availability can also compromise handwashing, sanitation and food hygiene (Dan-Hassan, 2026).
- Nigerian Case Illustration: Lagos Groundwater:
A study of borehole and well water in selected Lagos communities reported non-permissible concentrations of lead and nickel in sampled waters and microbiological concerns in some wells.
The study illustrates an important distinction: groundwater infrastructure can function mechanically while water quality remains a public health concern.
Lagos also demonstrates why urban hydrogeology must be considered in groundwater planning.
Dense sanitation systems, waste disposal, industrial activity, saline influence and changing recharge can interact with aquifer vulnerability.
The professional lesson is not that all Lagos boreholes are unsafe, but that urban groundwater systems require site-specific risk assessment and routine surveillance (Ige and Olaifa, 2013; Adewale et al., 2025).
- Case Illustration: Abule-Egba and the Waste–Groundwater Connection:
The source presentation includes a 2026 case illustration near the Abule-Egba dumpsite in Lagos, reporting groundwater-quality concerns in sampled boreholes, including elevated iron and lead in some samples and microbial contamination in leachate and groundwater (Edoka and Longe, 2026; Ige and Olaifa, 2013).
The presentation uses this example to demonstrate the interaction between waste sources, leachate migration, groundwater flow and public health.
The broader medical-geology lesson is that contamination risk depends not only on the presence of a contaminant source but also on hydrogeological connectivity.
A dumpsite does not automatically contaminate every nearby borehole; rather, the risk depends on geology, groundwater gradients, permeability, depth, recharge, contaminant mobility and borehole integrity.
Such cases therefore require integrated hydrogeological and environmental investigation.
- Institutional and Professional Causes:
Borehole failure is also an institutional problem.
The presentation identifies unqualified or inadequately supervised drilling, lowest-initial-cost procurement, insufficient investigation and documentation, weak enforcement, fragmented ownership, inadequate maintenance budgets and poor records as recurring governance risks
When procurement rewards the lowest initial price without considering technical quality and life-cycle cost, the apparent saving can become expensive through repeated breakdowns, rehabilitation and replacement.
Similarly, incomplete drilling logs and pump-test records make it difficult to diagnose failure and learn from previous projects.
A national borehole asset-management culture should therefore capture location, geology, depth, casing and screen details, yield, water levels, pump type, water quality, maintenance history and failure history.
16. NCP 027:2010: Standards as a Public Health Tool
The Nigerian Code of Practice for Water Well Construction (NCP 027:2010) provides a framework covering location, construction, maintenance and abandonment, with requirements relating to qualified personnel, equipment, procedures, groundwater protection and documentation (SON, 2010).
The presentation explicitly links these technical requirements to health protection: good construction reduces contamination pathways, proper completion protects aquifers, and maintenance helps prevent wells from becoming contamination channels.
The critical issue is implementation. Standards have limited value when they are not consistently incorporated into procurement, supervision, commissioning, inspection and professional accountability.
Compliance should be demonstrated through documentation and verification, not assumed from contract language.
17. Diagnosing A Failed Borehole:
A failed borehole should be diagnosed before intervention.
The presentation proposes a six-step protocol: review records; inspect the physical infrastructure; assess hydraulic performance; test water quality; interpret the evidence hydrogeologically; and decide whether to repair, rehabilitate, redesign, replace, deepen where technically justified or safely decommission.
Borehole Failure Diagnosis:
Records: Drilling log, lithology, casing/screen, pump test, quality and maintenance history.
Reconstruct: original design and performance.
Physical inspection: Headworks, drainage, seal, casing, pump, power and storage Identify visible/structural causes.
Hydraulic diagnosis: Static/pumping levels, discharge, drawdown, recovery, specific capacity, separate aquifer from equipment/construction problems.
Water quality : Microbiology, physicochemistry, metals and context-specific parameters Identify exposure hazards.
Hydrogeological interpretation: Geology, flow, recharge, land use and connectivity Identify root cause.
Decision: Repair, rehabilitate, redesign, replace or decommission Protect health and value.
- Rehabilitation, Replacement Or Decommissioning?
Rehabilitation should be selected according to the diagnosed failure.
Redevelopment may be appropriate where clogging or inadequate development is responsible.
Cleaning or descaling may be justified in suitable conditions. Pump replacement, resetting or rising-main repair can address equipment problems.
Sanitary-seal and headworks correction may be necessary where contamination pathways exist.
Water-quality problems may require source protection, treatment, blending or alternative supply.
Where rehabilitation cannot restore safe performance, controlled abandonment and replacement may be the responsible option.
The wrong intervention can be worse than no intervention. For example, repeatedly replacing a pump on a borehole affected by declining aquifer performance does not address the underlying hydraulic problem.
Similarly, repeated disinfection cannot substitute for correction of a defective sanitary seal.
- From ‘Drill and Abandon’ to Life-Cycle Asset Management
A sustainable approach requires a shift from project thinking to asset thinking. The full life cycle should include investigation, design, construction, commissioning, operation and maintenance, rehabilitation and decommissioning.
The presentation recommends borehole asset registers, preventive maintenance schedules, local technical capacity, spare parts planning and budgets that include maintenance and rehabilitation rather than capital construction alone.
- Public Health Risk Assessment and Surveillance
Risk assessment should link hazard, exposure pathway, health concern and priority action.
The lecture framework identifies microbial contamination as an acute concern requiring immediate investigation; fluoride as a source-specific chronic exposure requiring testing and a source or treatment strategy; arsenic and metals as requiring confirmation and exposure reduction; nitrate as requiring source protection and treatment or alternative supply; and salinity as requiring hydrochemical assessment and a source strategy.
Surveillance should combine operational and water-quality indicators. Static and pumping water levels, discharge, operating hours, specific capacity, turbidity, colour, taste, odour, pump energy use, breakdown frequency and sanitary inspection should be monitored.
Water-quality surveillance should include E. coli or appropriate microbial indicators, pH, electrical conductivity/total dissolved solids, temperature, major ions and context-specific geogenic parameters and metals (Yahaya et al., 2021).
- An Integrated Medical-Geology Framework for Nigeria
The proposed framework brings together six interacting domains: geology; hydrogeology; borehole engineering; water quality; public health; and governance.
Geology determines lithological, structural and mineralogical conditions.
Hydrogeology determines recharge, flow, storage and vulnerability.
Engineering determines how groundwater is accessed and protected.
Water quality determines the chemical, microbial and radiological characteristics of the resource.
Public health evaluates exposure, disease risk and equity.
Governance provides standards, monitoring, financing and accountability.
- A Nigerian Action Agenda:
- Make hydrogeological investigation mandatory: Publicly financed boreholes should be supported by appropriate geological and hydrogeological evidence before drilling.
- Strengthen professional supervision: Qualified personnel should oversee siting, drilling, completion, testing and commissioning.
- Make water quality a performance criterion: A borehole should not be accepted solely on the basis of yield.
- Enforce NCP 027:2010: Standards should be embedded in procurement, supervision, documentation and inspection.
- Build groundwater vulnerability and geogenic-risk maps: Priority contaminants should be linked to geological and hydrogeological settings.
- Establish borehole asset registers: Location, geology, construction, hydraulic, water-quality and maintenance data should be retained.
- Integrate WASH and medical-geology surveillance: Water service monitoring should connect with environmental health and exposure evidence.
- Adopt life-cycle costing: Maintenance, rehabilitation and monitoring should be financed from the beginning.
- Learn from failure: Failure databases should inform future siting, procurement and contractor-performance decisions.
- Conclusion: Redefining Borehole Success
Nigeria’s groundwater resources offer an essential foundation for water security, but groundwater development cannot be reduced to drilling holes and installing pumps.
Borehole failure is a multi-dimensional problem involving geology, hydrogeology, engineering, water chemistry, microbiology, public health, WASH and governance.
The medical-geology perspective is especially valuable because it connects the subsurface environment to human health. A mineralogical condition can influence groundwater chemistry; groundwater chemistry can create an exposure pathway; exposure can influence health.
Conversely, a defective borehole can create an anthropogenic pathway that changes the natural protection provided by the subsurface.
The professional challenge is therefore to redefine success. A successful borehole is not simply one in which water is encountered; it is a borehole that delivers water that is physically available, hydraulically sustainable, microbiologically safe, chemically acceptable, operationally reliable and socially accessible over its intended service life.
References and Technical Resources:
*Adewale ,A. O., Ali, H., Bakare-Abidola, T.,Akapo, S., Obayori, O. S. and Akinyemi, K. O. (2025). Comparative Quality Assessment of Water Samples from Protected and Unprotected Wells in Ayobo Area of Lagos State, Nigeria. Path of Science, Vol. 11, No. 12. DOI: 10: 22178/pos. 125-65.
*Centeno, J. A., Finkelman, R. B. and Selinus, O. (2016). Medical Geology: Impacts of the Natural Environment on Public Health. Geosciences, 6, 8, doi: 10.3390/geosciences6010008.
*Dan-Hassan, M. A. ( 2017). Review of Borehole Failures: Causes and Remedies. A paper Presented at the National Convention of the Association of Water Well Drilling Rig Owners and Practitioners (AWDROP) held at National Water Resources Institute, Kaduna, February 16, 2017.
*Dan-Hassan, M.A. (2026). Borehole Failures in Nigeria: Implications for Medical Geology and Public Health Perspectives. Nigerian Association of Hydrogeologists (NAH) Technical Presentation Webinar.
*Dan-Hassan, M. A. ( 2026). Framework for Water, Sanitation and Hygiene (WASH) in the Federal Capital Territory, Abuja, Nigeria. NIRPRI Publishers, Abuja, Nigeria, p. 336.
*Edoka, J. N. and Longe, E. O. (2026). Groundwater Quality Assessment near Abule-Egba Dumpsite, Lagos State, Nigeria: A Study of Physicochemical, Microbial Load and Heavy Metal Contaminants. Next Sustainability Journal, www.sciencedirect.com/journal/next-sustainability.
*Standards Organisation of Nigeria (2010). Nigeria Code of Practice for Water Well Construction, NCP 027: 2010, Nigerian Industrial Standard.
*World Health Organization (2026). Guidelines for drinking-water quality, fourth edition, incorporating the first, second and third addenda. WHO Geneva.
*Yahaya, T.O., Oladele, E.O., Fatodu, I.A., Abdulazeez, A. & Yeldu, Y.I. (2021). The concentration and health risk assessment of heavy metals and microorganisms in the groundwater of Lagos, Southwest Nigeria. Journal of Advances in Environmental Health Research, 8(3), 225-233.
*Above was presented at Jose A.Centeno International Centre for Medical Geology Research, Nasarawa State University, Keffi,Nigeria.
*The author, Dr. M.A. Dan-Hassan, until recently the multiple award-winning pioneer Executive Director, Federal Capital Territory (FCT) Rural Water Supply and Sanitation Directorate (RUWASSA), is one of Nigeria’s best brains in the field of Hydrogeology and Engineering Geology.
He holds a Bachelor’s degree in Applied Geology from Ahmadu Bello University (ABU, 1987);M.Sc. in Hydrogeology and Engineering Geology from Obafemi Awolowo University (Ile-Ife, 1993); and a Ph.D. in Hydrogeology from the Federal University of Technology, Minna (2013).
Dr. Dan-Hassan also earned professional certifications from Chalmers University of Technology in Sweden and the UNESCO-IHE Institute for Water Education in Delft, Netherlands.
