Biological and inorganic contaminants pose significant threats to ecosystems due to increasing environmental pollution. Conventional water treatment methods often struggle to remove these persistent pollutants, necessitating the need for advanced nanotechnology to enhance water and wastewater treatment. Nanotechnology offers promising solutions by improving water quality, promoting reuse and recycling, and enabling effective contaminant removal. This review article explores various nanoparticles, including organic and inorganic nanoparticles, silica nanoparticles, and nanocomposites, which have demonstrated remarkable efficiency in wastewater treatment. These nanoparticles act as potent disinfectants, efficient adsorbents, and effective catalysts for pollutant degradation. Their unique physicochemical properties at the nanoscale enable superior pollutant removal, including heavy metals, organic contaminants, and microbial pathogens. Despite significant advancements, challenges such as nanoparticle toxicity, cost-effectiveness, environmental impact, and large-scale applicability remain critical concerns. This review systematically examines different water pollutants and their consequences on living organisms, evaluates the suitability of nanoparticles for targeted contaminant removal, and highlights current challenges and future research directions in nano-enabled water treatment technologies.