Groundwater abstracted by boreholes is the principal source of drinking-water for the vast majority of Nigerian households, yet an increasing proportion of the country's water points are non-functional, poorly sited, or structurally damaged, thus exposing populations to a direct or indirect disease pathway. This paper systematically reviews the causes of borehole failure in Nigeria and collates associated health impacts. A systematic review was conducted in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 guidelines. Pub Med, Scopus, Google Scholar, African Journals Online, UN and related agency repositories were systematically searched for records in English published 01/2020-09/2026 using keyword combinations of 'borehole' OR 'groundwater' AND 'water infrastructure failure' OR 'water quality' OR 'waterborne disease' OR 'cholera' AND 'Nigeria'. Eligible records presented primary data, secondary evidence or systematic evidence on borehole quality, groundwater contamination, or cholera, typhoid or diarrhoeal disease in Nigeria. Screening, eligibility assessment, and thematic synthesis were performed in accordance with PRISMA guidance. Results Evidence synthesis converged on the conclusion that an estimated one-third- to one-half of Nigeria's improved water sources, boreholes especially, are permanently non-functional or deliver contaminated water at any given time, by a confluence of operational, financial, environmental, political, institutional and technical failures. These failure modes are associated with waterborne faecal coliforms, microplastics and heavy metals in many states. Borehole failure must be understood and addressed as a population health issue, not only an engineering or infrastructure challenge. Key interventions include enforcing well siting and construction standards, establishing routine groundwater quality monitoring systems, and integrating WASH and other water-related public health indicators into public health policy. Keywords: borehole failure; groundwater contamination; water, sanitation and hygiene (WASH); waterborne disease; cholera; Nigeria; systematic review; public health.