Community water treatment systems (CWTS) are crucial for improving access to safe drinking water in Mozambique's dry regions where vulnerable villagers often face challenges accessing clean water. A mixed-method approach combining quantitative data on CWTS usage and qualitative interviews with community members was employed to analyse the impact of CWTS implementation in three dry regions of Mozambique. CWTS adoption rates were found to increase by 45% within two years post-installation, correlating with a significant reduction in waterborne diseases (p < 0.01). The study underscores the effectiveness of CWTS in enhancing public health outcomes and economic stability among vulnerable populations in Mozambique's dry regions. Policy makers should prioritise the provision of CWTS to support sustainable development goals, especially in underserved rural areas. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.