Abstract: The disclosed technology can generally relate to methods for manufacturing spent coffee ground derived microbots for purifying contaminated water sources. The method for manufacturing the spent coffee ground derived microbots can include obtaining coffee grounds, magnetizing the coffee grounds, and coating the magnetized coffee ground with ascorbic acid. Magnetizing the coffee grounds can include immersing the coffee ground in a solution of iron oxide nanoparticles and ethanol, mixing the coffee grounds and the solution, and allowing the coffee grounds and the solution to sit undisturbed for a predetermined period.