Concrete is the most predominately used construction material for wastewater collection and treatment facilities. Nevertheless, there are still many questions and misconceptions on how to properly evaluate this substrate prior to commencing a coating or lining project. Knowing how to address any defects or necessary repairs is imperative for all projects, but in many cases, some of these repairs or details are omitted. In turn, questions still arise from the field on how to properly prepare these surfaces. Answering these questions is a vital task, as surface preparation is a major component in the successful installation of protective linings or polymer concretes. The main goal for any concrete coating project is the long-term protection of the substrate from corrosive and physical forces, which cannot be achieved without all these key steps taking place prior to placing the asset into immersion or chemical containment service. In summary, this paper will review the common forms of concrete attack mechanisms that occur in wastewater environments and will also review current industry best practices to repair (and prepare) concrete prior to the application of polymer concretes or high-performance protective linings. Some select case histories will be discussed in order to illustrate some of the concepts covered throughout the paper.