Many cultures, since the early Bronze Age, have found ways to use or dispose of domestic wastewater for purposes such as irrigation and fish farming – China, Egypt, and Mesopotamia, are just some examples. During historical times (ca. 1000 BC−330 AD), both Greek and later Roman empires utilized wastewater in this way surrounding larger cities like Athens and Rome.
Through the years, water recycling has become more prevalent and extensive, to the point where it is now used for any purpose, even drinking. As mega-cities continue to grow, the traditional concept of a single wastewater treatment plant (WWTP) for all sewage is no longer practical. Decentralization is necessary and will provide more chances for local water reuse. The new technologies being implemented as well as those still in development will cause a shift in how we view conventional and advanced wastewater treatments.