dirty water; sewage; wastewater
Refers to water contaminated by domestic, industrial, or agricultural waste. Often used in environmental, engineering, or public health contexts.
Wastewater from factories must be purified before being released into rivers.
In this area, treatment of domestic sewage is a major challenge.
The wastewater from the factory is treated before being released into the river.
Due to the heavy rain, wastewater flowed into the sea.
This factory was discharging wastewater that exceeded the standards.
排水 refers to water that has been drained or discharged and is not necessarily dirty, whereas 汚水 specifically emphasizes contamination.
廃水 is a more technical term for industrial wastewater discharged from factories, while 汚水 covers contaminated water from any source, including households.
Compound of 汚 (お, 'dirty') and 水 (すい, 'water'). The reading おすい is a straightforward on'yomi combination.