This publication provides introductory technical guidance for environmental engineers, civil engineers and other professional engineers and construction managers interested in water treatment using coagulation and flocculation methods. Here is what is discussed: 1. INTRODUCTION, 2. COAGULANTS, POLYELECTROLYTES, AND COAGULANT AIDS, 3. MIXING - GENERAL DISCUSSION AND THEORY, 4. TREATABILITY TESTING, 5. PRE-TREATMENT REQUIREMENTS