Wastewater is collected from customers, traveling through sewer pipes to wastewater treatment plants where it is treated and returned to streams, rivers, and oceans, or reused for irrigation and landscaping. Operators in both types of plants control processes and equipment to remove solid materials, chemical compounds, and micro-organisms from the water or to render them harmless. They also control pumps, valves, and other processing equipment to move the water or wastewater through the various treatment processes, and dispose of the waste materials removed from the water. Operators read and interpret meters and gauges to make sure plant equipment and processes are working properly and adjust controls as needed. They operate chemical-feeding devices, take samples of the water or wastewater, perform chemical and biological laboratory analyses, and test and adjust the amount of chemicals such as chlorine in the water.
Operators also make minor repairs to valves, pumps, and other equipment.
They use a variety of instruments to sample and measure water quality, gauges, and common hand and power tools to make repairs. Water and wastewater treatment plant operators increasingly rely on computers to help monitor equipment, store sampling results, make process control decisions, schedule and record maintenance activities, and produce reports. When problems occur, operators may use their computers to determine the cause of and solution to the malfunction. Occasionally operators must work under emergency conditions. A heavy rainstorm, for example, may cause large amounts of wastewater to flow into sewers, exceeding a plant's treatment capacity.