Water is an essential component of Earth’s ecosystem, yet its quality is rapidly deteriorating due to the increasing presence of pollutants, including emerging contaminants like pharmaceutical residues. These pollutants pose severe risks to human health by disrupting enzymatic, hormonal, and genetic systems. To address this, various water treatment methods have been developed, including filtration, oxidation, coagulation, and reverse osmosis. Among these, adsorption has proven to be one of the most effective approaches due to its simplicity and wide applicability. Initially, activated carbon was the primary adsorbent used, but more cost-effective alternatives have since emerged. With advancements in nanotechnology, nano-adsorbents have become the new generation of materials used in water treatment, offering high adsorption capacities under diverse conditions and removing contaminants at trace levels. These nano-adsorbents, including carbon-based materials like carbon nanotubes and graphene, as well as metal-oxide nanoparticles, have shown exceptional effectiveness in treating heavy metals and other pollutants. As industrialization and population growth continue to exacerbate water contamination, the development and application of innovative nano-based adsorption techniques are crucial for safeguarding both human and environmental health. Nanotechnology’s eco-friendly fabrication and high affinity for a variety of contaminants make it a promising solution for future water treatment challenges.