PFAS Action Act of 2021 This bill establishes requirements and incentives to limit the use of perfluoroalkyl and polyfluoroalkyl substances, commonly referred to as PFAS, and remediate PFAS in the environment. PFAS are man-made and may have adverse human health effects. A variety of products contain PFAS, such as nonstick cookware or weatherproof clothing. The bill directs the Environmental Protection Agency (EPA) to designate the PFAS perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as a hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, thereby requiring remediation of releases of those PFAS into the environment. Within five years, the EPA must determine whether the remaining PFAS should be designated as hazardous substances. The EPA must publish human health water quality criteria under the Clean Water Act for each measurable PFAS and class of such substances and establish standards to limit discharges of PFAS from industrial sources into waters of the United States. In addition, the EPA must issue a national primary drinking water regulation for PFAS that, at a minimum, includes standards for PFOA and PFOS. Among other requirements, the EPA must also issue a final rule adding PFOA and PFOS to the list of hazardous air pollutants, test all PFAS for toxicity to human health, and regulate the disposal of materials containing PFAS. The EPA must also require PFAS manufacturers to submit analytical reference standards for PFAS. The EPA and states may use those standards for (1) the development of information, protocols, and methodologies, and (2) activities relating to the implementation of enforcement of requirements. Finally, the bill provides incentives to address PFAS, such as grants to help community water systems treat water contaminated by PFAS and grants to schools for testing and filtrating PFAS from drinking water.