History of water reuse

The practice of recycling previously used water for secondary purposes has a long history. Early evidence of agricultural irrigation with wastewater can be found in Crete and Greece dating as far back as the early Bronze Age (3000 BC). Roman systems for harvesting rainwater from rooftops for domestic uses have also been discovered in cities such as Pompeii (6BC-7AD). The reuse of wastewater as a nutrient source in aquaculture has been practised for hundreds of years around the world. Vestiges of fishponds purposely build to receive nutrient-rich wastewater diverted from abbey latrines dating from the 13th century have been discovered in Germany and France. In the 19th century, unintended wastewater reuse also took place in various countries through the operation of sewage farms originally engineered for sanitation purposes, where wastewater was applied to land to benefit from its fertilising value.

However, it is only from the beginning of the 20th century that planned water reuse started to be seen as an opportunity to increase the efficiency of water use and limit the abstraction of freshwater from rivers and aquifers. For instance, early developments of engineered water reuse systems for irrigation are reported from the 1920s in California. In the 1950s, Japan started reusing wastewater for industrial applications. From the 1960s, crop irrigation with reclaimed wastewater was becoming common practice in Israel and other Mediterranean countries, while in 1968 the city of Windhoek in Namibia implemented the first advanced direct wastewater reclamation system to augment potable water supplies. In 1984, the Tokyo Metropolitan Government pioneered the use of reclaimed water for toilet flushing in 19 high-rise buildings in the Tokyoite Shinjuku district. Since the 1980s, thousands of water reuse projects have been developed around the world, and it is estimated that more than 200 water-recycling schemes are in operation in the European Union.