Nanosciences and nanotechnologies are new approaches to research and development that concern the study of phenomena and manipulation of materials at atomic, molecular, and macromolecular scales, where properties differ significantly from those at a larger scale. Nanotechnology could help to a better comprehension of the pharmacokinetic and biodistribution of toxins in the human body when they are consumed. Great efforts are being made to explore the potential impact of nanotechnology in water management at different fronts, namely, prevention of pollution, treatment and remediation, and sensing and detection. Toxins of different biochemical natures and pathological effects require customized processes of sample extraction, purification, and detection. Toxin analysis is benefiting from the advances of applying nanomaterials to biosensors development. In particular for the field of aquatic toxin analysis, biosensor technologies can offer cost-effective solutions with suitable characteristics of group specificity, sensitivity, repeatability, and robustness.