This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on performing titration analysis for water quality. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming each part of the titrating apparatus and telling how each works or is used; (2) getting the titrating apparatus ready for use by putting it together and by cleaning the buret; and (3) reaching the endpoint of a titration to standardize the titrating solution, sodium thiosulfate. Each lesson contains objectives, recommended methods and locations for practice, performance criteria, equipment and supplies to perform a task, detailed step-by-step instructions for learning a task, and performance exercises. Two performance tests cover preparing the titration apparatus and doing a titration to standardize the titrant.