Safe and reliable water is essential for healthcare delivery, yet many hospitals in Nigeria depend on borehole water whose quality is seldom comprehensively assessed. This study evaluated the hydrochemical characteristics, microbiological quality, and public health risks associated with borehole water used in selected hospitals in Rivers State, Nigeria. Twelve anonymised borehole water samples (HBW-01–HBW-12) were collected and analysed in triplicate using standard analytical procedures. Physicochemical parameters, major ions, heavy metals, microbiological indicators, Water Quality Index (WQI), non-carcinogenic health risk, Pearson correlation, and Principal Component Analysis (PCA) were determined. Water temperature ranged from 27.20–29.60°C, while pH varied between 5.91 and 7.28, with four boreholes exhibiting slightly acidic conditions. Electrical conductivity (185.6–612.4 µS/cm), total dissolved solids (118.4–396.7 mg/L), nitrate (3.41–17.86 mg/L), biochemical oxygen demand (1.42–3.52 mg/L), and major ions remained within World Health Organization (WHO) guideline limits. However, iron concentrations reached 0.69 mg/L, while lead (0.002–0.022 mg/L) and cadmium (0.0002–0.0050 mg/L) exceeded permissible limits in several boreholes. Total coliforms were detected in ten boreholes and Escherichia coli in five, whereas Salmonella spp. and Vibrio spp. were absent. WQI classified six boreholes as excellent, three as good, two as poor, and one as unsuitable for drinking. Hazard Quotient values remained below unity for adults but exceeded acceptable limits for children in several locations, with Hazard Index values indicating cumulative non-carcinogenic risks among children. Pearson correlation showed a strong relationship between electrical conductivity and total dissolved solids (r = 0.91), while PCA identified groundwater mineralisation, heavy metal contamination, and hydrogeochemical weathering as the dominant processes controlling water quality. Although most physicochemical parameters complied with WHO standards, heavy metal contamination and microbial pollution in several boreholes present significant public health concerns, highlighting the need for routine monitoring, water treatment, and improved borehole management within hospital environments.
