This publication provides introductory technical guidance for civil engineers, environmental engineers, mechanical engineers and other professional engineers and operation and maintenance personnel interested in sampling and testing of 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.