Water Pollution & Wastewater Treatment Water Pollution: Sources and Impacts Water is one of our most valuable natural resources—and one of the most vulnerable to pollution. Water pollution occurs when harmful substances, including chemicals, microorganisms, industrial waste, and other contaminants, enter water bodies such as rivers, lakes, streams, groundwater, and oceans. These pollutants can degrade water quality, damage aquatic ecosystems, and make water unsafe for human consumption or use. Major sources of water pollution include industrial and commercial wastewater, agricultural runoff, municipal wastewater, oil pollution, mining activities, and radioactive substances. The effects of water pollution can extend throughout the entire water system. Contaminated groundwater can threaten drinking-water supplies, while pollutants discharged into rivers and lakes can harm aquatic organisms and eventually reach marine environments. Understanding Industrial Wastewater Industrial wastewater is water discharged from manufacturing, processing, mining,