Design of a multi-stage, low-cost filtration system for safe drinking water in Urban informal settlements

Access to safe and reliable drinking water remains a critical challenge in urban informal settlements, particularly in Mukuru, Nairobi, Kenya, where inadequate supply and poor water quality have led to recurrent outbreaks of waterborne diseases such as cholera and typhoid. Only 1% of residents have acess to individual water sources, with an average of 234 households sharing a single source and receiving approximately 1.8m³ of water monthly. As a result, households depend on costly informal water markets for daily needs. This study evaluated the accessibility and quality of available. This study evaluated the accessibility and quality of available water sources against local and World Health Organization (WHO) standards, assessing parameters including pH, total dissolved solids (TDS), and total suspended solids (TSS), turbidity, electrical conductivity (EC), salinity, color, fluoride, and microbial contamination indicators such as total coliforms and Escherichia coli. Findings revealed that both rainwater and borehole water sources fail to meet WHO guidelines, with critical exceedances in turbidity, TSS, microbial load, and fluoride levels (6.2 mg/L). To address these challenges, the study explores the development of low-cost, sustainable filtration technologies using locally available natural materials, specifically kieselghur and kaolin clay. Material characterization and performance evaluation were conducted to assess their suitability for contaminant removal, including fluoride and pathogens. The proposed multi-stage filtration systems emphasize affordability, local availability, and operational simplicity, aligning with the needs of low-income urban communities. This research contributes to scalable, nature-based solutions aimed at improving water quality and promoting sustainable access to safe drinking water in resource-constrained urban settings.