**Abstract**

Water has become a major threat in today's world. Collection of heavy metals, a few of them, is potentially toxic and these get distributed to different areas through different pathways. With an increase in the earth's population, development and industrialization are taking place rapidly and these get the major source of water contamination. With heavy metals in lakes, rivers, groundwater, and various water sources, water gets polluted by the increased concentration of heavy metals and metalloids through release from the suddenly mine tailings, disposal of high metal wastes, growing industrial areas, leaded gasoline and paints, usage of fertilizers inland, animal manures, E-waste, sewage sludge, pesticides, wastewater irrigation, coal, etc. Exposure to heavy metals has been linked to chronic and acute toxicity, which develops retardation; neurotoxicity can damage the kidneys, lead to the development of different cancers, damage the liver and lungs; bones can become fragile; and there are even chances of death in case of huge amount of exposure. This chapter mainly focuses on heavy metal pollution in water and its toxic effect on living organisms.

**Keywords:** heavy metal, water, toxicity, pollution, living organisms
