Present chapter veritable on indispensable need to avert water deficiency amongst existing accelerating living population to maintain ecological balance via utilizing waste water with ensued effective treatment and disinfection. There is an imperative need to work in the domain of modern wastewater treatment technologies with proliferating efficacies and low capital requirement. Therefore, water contaminants need to be shackled at appropriate time to ensure its effective treatment and disinfection. Nanosensors on account of their high aspect ratio, enhanced surface, optical, magnetic, electrical and spectroscopic properties, portability and flexibility in comparison to bulk materials may prove as promising early warning alarms with ensued effective waste water treatments. Moreover, high adsorption capacity of nanosensors ensures effective detection and obviation of microorganisms and other metal contaminants in water. The role of chemresistors and other nanosensors techniques for the detection and treatment of waste water are demonstrated and analyzed in this chapter.