This book provides information on how to design systems to remove major groups of drinking water contaminants, including hardness, total organic carbon (TOC), radionuclides, arsenic, nitrate, perchlorate, chromium, and PFAS. Each chapter discusses the regulatory issues associated with the specific contaminant, source water qualities that can impact the resin, bench and pilot-testing requirements, and design guidelines. Case studies illustrate how design principles and best practices can be implemented in the field.