Per-and polyfluoroalkyl substances (PFAS) have been identified as widespread environmental contaminants of concern. Traditional pump and treat systems are expensive, with no clear end point. Novel destructive methods are still in early development stages and may be inefficient in the treatment of widespread, dilute plumes. Colloidal activated carbon (CAC) is now be deployed as a practical and cost-effective in situ method to eliminate the risk associated with PFAS compounds in groundwater. This approach has been deployed on nineteen sites across Europe, the USA, Canada and Middle East and this presentation illustrates the design, application and validation of the remedial process of those sites.