Slow sand filters for the 21st century

Safe drinking water remains a major global challenge, especially in rural areas where, according to UNICEF, 80% of those without access to improved water supply systems live. Slow sand filters (SPFs) are an ideal solution for preparing drinking water in such areas. SPFs allow the removal of suspended particles, dissolved organic matter, and other pollutants, thereby eliminating turbidity, taste, and odor. Additionally, one of the most important aspects of applying SPF is its function as a biological filter. Although the principle of SPFs operation has remained the same for more than two centuries, the design, size, and application of SPFs have been changed over the years and adapted to specific needs. This paper discusses modern solutions and the efficiency of SPFs in terms of removing specific pollutants, primarily turbidity and microorganisms, which are of particular importance for the preparation of drinking water in rural areas.