Water is the most important natural resource on Earth for human development and all living beings’ existence. Urbanization and industrialization are the main causes of the sharp rise in water consumption. In the twenty-first century, water pollution due to heavy metals is a serious environmental issue. Though heavy metals are present at the trace level in the natural environment, due to biomagnification and bioaccumulation phenomena, they show hazardous effects on the environment and human beings. Due to the rise in the global population, discharges of contaminated waste from industrial, agricultural, and domestic had increased manifolds and ultimately they reach the water sources. In many instances, the removal efficiencies of conventional treatment procedures are insufficient. On the other hand, a newly created sophisticated treatment method, nanotechnology, has widespread applicability in various fields of research and it is paving the way to find suitable methods for the treatment of wastewater. Nanomaterials are biodegradable, have a high specific surface area, play a key role in polar and nonpolar chemistry, have high adsorption capacity, and have controlled and tunable size making them suitable candidates for remediation of water. In this chapter, nanomaterials of carbon-based nanomaterials (carbon nanotubes, carbon nanofibers, graphene, and fullerenes) and non-carbon origins such as nanoparticles of double-layered hydroxides, nanomaterials of metal oxide origin (Fe, Al, Ti, Mg, and Mn,), nanoclay (Kaolin, montmorillonite and zeolite), dendrimers, nanomaterials based on zero-valent metal (Fe, Ag, and Au) and silica nanomaterials benefits, drawbacks, and efficiency were discussed.