This publication provides introductory technical guidance for mechanical engineers and other professional engineers, construction managers and facility managers interested in sampling and testing of industrial water systems, such cooling tower water systems. Here is what is discussed: 1. WATER SAMPLING AND TESTING, 2. COOLING TOWER WATER SAMPLING AND TESTING, 3. ROUTINE BOILER WATER SAMPLING AND TESTING, 4. WATER SAMPLING AND TESTING FOR CLOSED HOT AND CHILLED CIRCULATING WATER SYSTEMS, 5. WATER TESTING, 6. INTERPRETATION OF RESULTS FROM WATER TESTS, 7. IN-PLANT LABORATORY WATER TESTING REQUIREMENTS.