Grey water is all wastewater generated in households or office buildings from streams without faecal contamination, i.e. all streams except for the wastewater from toilets. Sources of grey water include, sinks, showers, baths, clothes washing machines or dish washers. As grey water contains fewer pathogens than domestic wastewater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation and other non-potable uses. However, the use of non-toxic and low-sodium soap and personal care products is recommended to protect vegetation when reusing grey water for irrigation purposes. The application of grey water reuse in urban water systems provides substantial benefits for both the water supply subsystem by reducing the demand for fresh clean water as well as the wastewater subsystems by reducing the amount of wastewater required to be conveyed and treated.
According to SSWARS the following are some of the benefits of proper grey water management;
- Reduced freshwater extraction from rivers.
- Less impact from septic tank and treatment plant infrastructure
- Reduced energy use and chemical pollution from treatment
- Ground water recharge
- Reclamation of nutrients