{ "background": "The adoption of engineered water treatment systems in sub-Saharan Africa is critical for public health, yet robust methodological frameworks for analysing adoption determinants are lacking. Existing studies often fail to account for the hierarchical structure of data, where individual households are nested within communities with shared infrastructural and governance contexts.", "purpose and objectives": "This study presents a methodological evaluation of multilevel regression modelling for analysing the adoption of household water treatment systems. Its objective is to demonstrate the application and advantages of this technique over conventional single-level models in identifying significant predictors at both household and community levels.", "methodology": "A cross-sectional dataset from a national survey was analysed using a two-level logistic regression model. The model specified the log-odds of adoption for household $i$ in community $j$ as $\\text{logit}(p{ij}) = \\beta{0j} + \\beta{1}X{1ij} + ... + \\beta{k}X{kij}$, with $\\beta{0j} = \\gamma{00} + \\gamma{01}Z{1j} + u{0j}$, where $u{0j} \\sim N(0, \\sigma^2_u)$. Model fit was assessed using the intraclass correlation coefficient and likelihood ratio tests.", "findings": "The multilevel model revealed that 32% of the variance in adoption was attributable to community-level factors, a finding masked by a standard logistic regression. A key concrete result is that household income was a significant positive predictor (odds ratio 1.85, 95% CI 1.62 to 2.11), but its effect was moderated by the presence of a community maintenance programme.", "conclusion": "Multilevel regression provides a superior methodological framework for engineering adoption studies by quantifying contextual effects and preventing ecological fallacy. Its use is recommended for planning and evaluating water infrastructure projects where data is hierarchically structured.", "recommendations": "Future engineering surveys should be designed to collect hierarchical data. Polic