Grey water is household wastewater except that from toilets. Kitchen waste water is not recommended for untreated re-use because it has large amounts of grease, fats and food waste.
Grey water is made up of the wastewater from our showers, baths, spas, hand basins, laundry tubs, washing machines, dishwashers and kitchen sinks. (It doesn't include water from toilets.) Used appropriately, you can water your garden with grey water and save around 400 litres of fresh water each day.