Clean Water Standards for PFAS Act of 2021 This bill directs the Environmental Protection Agency (EPA) to develop requirements and incentives to limit the discharge of perfluoroalkyl and polyfluoroalkyl substances (PFAS) into certain waters of the United States. PFAS are man-made and may have adverse human health effects. A variety of products contain the compounds, such as nonstick cookware or weatherproof clothing. Within two years, the EPA must publish water quality criteria for each measurable perfluoroalkyl substance, polyfluoroalkyl substance, and class of PFAS. The water quality criteria must determine how much of these substances can be present in water before it is likely to harm human health. Within four years, the EPA must publish a final rule that establishes, for each priority industry category specified in the bill, effluent limitations guidelines and standards for the discharge of each measurable perfluoroalkyl substance, polyfluoroalkyl substance, and class of PFAS. Under the Clean Water Act, effluent limitations restrict the quantities, rates, and concentrations of chemical, physical, biological, and other constituents which are discharged from point sources (e.g., a discernible source such as a pipe) into navigable waters, the ocean, or other specified waters. In addition, the EPA must award grants to owners and operators of publicly owned treatment works for implementing the effluent limitations guidelines and standards.