A professional who analyzes water in purification plant to control chemical processes which soften it or make it suitable for drinking. Responsibilities include:

• Analyzes samples of filtered water to ensure that quantities of solids left in suspension are below prescribed limits.
• Determines amounts of liquid chlorine to be used in chlorinators to destroy microbes and other harmful organisms, basing amounts on findings of microbiologist.
• Determines kinds and amounts of chemicals to be used in removing minerals, acids, salts, and other inorganic compounds from water to soften it.
• Tests samples extracted from various points in distribution system, such as mains, tanks, pumps, and outlets, to discover possible sources of water contamination.