This project includes the study of dividing root tip cells under normal conditions, finding the mitotic index as well as exposing the root tips to different chemicals to see the effect on the mitotic index and chromosomes. Nanotechnology is an emerging branch of science. Nano particles have unique physical and chemical properties and thus used in diverse applications Here Nanoparticles are used for water treatment and thus enriching the quality of water. Onion root tips were exposed to different concentrations such as 10ppm, 50ppm and 100ppm at different time durations such as 12h, 24h, 22h.at different concentrations and time durations toxicity of chemicals was checked. Chromosomal aberrations were observed. Nano fibres are used to filter the polluted water sample. Analysis of pol-luted water before and after the filtration is done by pH, conductivity, chloride test and turbidity. It was found that after treatment of polluted water using carbon nanofibers (CNFs) there is a drastic improvement in the water quali-ty. Lead Acetate and copper oxide in polluted water deteriorate the quality of onions thus having negative effects on humans.