Greywater is specifically washwater. That is, bath, dish, and laundry water excluding toilet wastes and free of garbage-grinder residues. When properly managed, greywater can be a valuable resource which horticultural and agricultural growers as well as home gardeners can benefit from. It can also be valuable to landscape planners, builders, developers and contractors because of the design and landscaping advantages of on-site greywater treatment/management. It is, after all, the same phosphorous, potassium and nitrogen making greywater a source of pollution for lakes, rivers and ground water which are excellent nutrient sources for vegetation when this particular form of wastewater is made available for irrigation.
The presence of micropollutants, such as pharmaceuticals and ingredients of personal care products, in the environment has proven to cause harmful effects in the aquatic environment. The major source of these micropollutants is domestic wastewater. In grey water, micropollutants can be present in considerable quantity as well .
These micropollutants originate mainly from personal care and household products, which contain fragrances, surfactants, preservatives, UV- filters, plasticizers and biocides. Many of these compounds are endocrine disruptors. For instance, the fragrances galaxolide and tonalide have been proven to cause anti-androgenic effects in vitro and in vivo tests.
Ozonation and adsorption onto activated carbon are very effective techniques to reduce the load of micropollutants from wastewaters.