Drinking Water Contaminants and Advanced Purification Technologies: A Review of Conventional and Emerging Treatment Approaches

Freshwater contamination has become a critical global challenge, driven by industrialization, urbanization, agriculture and climate change, threatening safe drinking water and sustainable development. This review synthesizes peer-reviewed literature identified through targeted searches of major bibliographic databases, including Scopus, Web of Science Core Collection and PubMed, with Google Scholar used as supplementary search tool, using contaminant- and technology-specific keywords. Conventional treatment processes, including coagulation–flocculation, sedimentation, filtration, adsorption, activated carbon, ion exchange and chemical disinfection, are critically evaluated alongside advanced technologies such as membrane filtration, reverse osmosis, nanofiltration, advanced oxidation processes (including photocatalysis), electrochemical treatment and nanotechnology-based systems, with emphasis on mechanisms, removal efficiency and operational limitations. Evidence indicates that adsorption-based technologies (GAC/PAC) achieve up to 97% removal of long-chain PFAS following advanced regeneration, coagulation–sedimentation removes up to 95% of microplastics, and precipitation-based processes achieve 70–99% removal of heavy metals, yet no single technology addresses the full contaminant spectrum across varying water quality conditions. Integrated multi-barrier systems combining conventional and advanced technologies therefore provide the most effective and sustainable approach for producing safe drinking water. The review also examines emerging trends, including smart water treatment systems, advanced functional materials, renewable energy integration, and circular water management and identifies key research gaps and priorities for cost-effective, energy-efficient and resilient purification technologies essential to global water security and supporting the achievement of Sustainable Development Goal 6 (Clean Water and Sanitation).