Background: Despite substantial investments in rural water infrastructure across sub-Saharan Africa, functionality deficits and water quality problems continue to undermine public health gains. This study assessed water, sanitation, and hygiene (WASH) service status in rural Chama District, Zambia, examining how service reliability, water quality, and governance arrangements influenced health outcomes.

Methods: A convergent mixed-methods design integrated a household survey (n=400), microbiological water quality testing (n=200 samples), key-informant interviews (n=34), and focus-group discussions (n=6 groups, 54 participants) across 12 rural wards during dry and rainy seasons (2025). Quantitative data were analysed using descriptive statistics and logistic regression in SPSS v.27; qualitative data underwent thematic analysis in NVivo v.12. Data triangulation synthesised numerical patterns with institutional and behavioural explanations.

Results: While 65% of households reported using improved water sources, only 54% of tested sources were microbiologically safe (E. coli=0 CFU/100mL), and 40% of households experienced primary source non-functionality in the preceding month. Improved latrine coverage was 30%; handwashing stations with soap were observed in 35% of households. Logistic regression revealed that households using unsafe water sources had 2.70 times higher odds of reporting under-five diarrheal episodes (95% CI: 1.55–4.71, p=0.001), while recent source non-functionality increased odds by 1.85 (95% CI: 1.05–3.27, p=0.033). Women spent a mean of 18.2 hours weekly collecting water, correlating with elevated school absenteeism among girls. Qualitative analysis identified spare-parts shortages (median repair time 18 days), weak maintenance financing (only 20% of households paid water fees), and limited female representation in Water Point Management Committees as principal institutional barriers.

Conclusions: Nominal infrastructure coverage substantially overstated reliable, safe WASH access. Microbial contamination and service interruptions were significant predictors of diarrheal disease. Sustainable improvements require integrated interventions addressing spare-parts supply chains, transparent maintenance financing, gender-inclusive governance, and targeted water quality monitoring rather than infrastructure expansion alone.