Access to safe drinking water is universally recognized as a fundamental human right; however, millions of people worldwide continue to face limited access to clean and safe water resources. The presence of contaminants such as heavy metals, organic compounds, dyes, pesticides, pharmaceuticals, and pathogenic microorganisms poses significant threats to human health and aquatic ecosystems. Conventional water treatment technologies, although effective in certain applications, are often associated with high operational costs, energy requirements, and limited efficiency toward emerging pollutants. Consequently, the development of sustainable, low-cost, and efficient water purification materials has gained increasing scientific attention. This review investigates the effectiveness of activated carbon as a promising adsorbent for drinking water purification and examines the principal mechanisms involved in pollutant removal. Various forms of activated carbon produced from agricultural waste-derived precursors were comparatively evaluated. Reported studies indicate that activated carbon exhibits a high specific surface area ranging from 300 to 2500 m².g⁻¹ and achieves removal efficiencies exceeding 90% for volatile organic compounds (VOCs), chlorine, dyes, and toxic heavy metals including Pb²⁺, Cd²⁺, and Cr⁶⁺. The adsorption capacities of activated carbon for different contaminants were reported to range from 50 to more than 500 mg.g⁻¹, depending on precursor type, activation process, and operational conditions. Furthermore, regeneration efficiencies commonly remained within 70–85% after multiple adsorption–desorption cycles, highlighting the economic feasibility and environmental sustainability of activated carbon.