What is Greywater?

Greywater is defined as any form of wastewater which is produced in the household from every source but the toilet. For example, greywater comes from the used water in the kitchen (dishwasher, sink), bathroom (sink, tub, shower) or from doing the laundry (washing machine).

Properties of Greywater

Greywater has the advantage that it contains little organic matter, and that, in comparison to blackwater, is only slightly contaminated. While it is low in nutrients, it also has only minimal bacterial concentrations and relatively small amounts of drug residues. Greywater is much easier to clean than ordinary sewage because its properties allow a much simpler, gentler and less energy-intensive cleaning process.

Greywater in the HAMBURG WATER Cycle®

In general, greywater and blackwater are combined with rainwater and transported together as sewage to a treatment plant where it is then cleaned. The HWC concept demonstrates new methods of wastewater treatment. In this concept the waste can be transported independent of centralized infrastructure and black-, grey-, and rainwater are recycled, providing an efficient and ecological use of different waste streams. In the HWC, greywater is thus always separated from the blackwater, and then the greywater is clarified in a specially designated facility and finally introduced into the local waters. Alternatively, it is also possible to reuse the greywater as process water for household activities such as watering the garden or toilet flushing for example.