Book excerpt: The Wastewater Operator's Guide to Preparing for the Certification Examination was prepared jointly by the Water Environment Federation, the Association of Boards of Certification(ABC), and the Certification Commission for Environmental Professionals (C2EP). It outlines what you can expect from the exam, provides key formulas, and lets you test your skills with sample questions. Updated job tasks and types of knowledge are addressed in four levels of competency. The approximately 200 questions included in this guide have been chosen to sample as many different aspects of a wastewater operator's job responsibilities as possible. Questions in the study guide are intended to provide an example of style and possible topics for certification exam questions. This guide includes C2EP 's education and experience requirements, tips for taking a certification examination, and sample formulas and conversions. Detailed answers to mathematical problems and references are provided