"오수" refers to the concept of "wastewater" in Korean. It encompasses all types of used water that come from households, industries, and agricultural activities. This water often contains various pollutants and requires treatment before it can be safely released into the environment. The management of 오수 is crucial for public health and environmental protection. Treatment facilities, known as 하수 처리장, are designed to clean this wastewater by removing harmful substances. Proper treatment helps prevent contamination of 지하수 and 수역, ensuring safe water for both human use and aquatic ecosystems.