Waste waters are any liquid waste materials produced by human activities at home, industry, or commerce. There are different synonyms for the term "waste waters" depending on its origin. For wastewater that comes from domestic activities, an appropriate synonym is sewage or greywater. For industrial wastewater, the term process water or effluent is more suitable. Another synonym that applies to wastewater in general is contaminated water. Moreover, the term used highly depends on the level of contamination and the treatment required. Overall, understanding synonyms for waste water is essential in identifying the source and treatment required to maintain the good health of our environment.