Typically, two thirds of the water used in a house results in graywater (excluding water used for the garden and lawns).Blackwater is household waste water that includes:
Darkwater is household waste water from the kitchen. It may contain food contaminants, oils and powerful detergents (especially dishwashers). Graywater Names
Although many jurisdictions ban the re-use of kitchen water (Darkwater), in some situations this water may be used for garden irrigation IF a grease trap is installed between the kitchen waste outlet and a graywater pumping system.
The above definitions apply generally throughout the world, although exact definitions vary from country to country, and in the US from state to state.
Practical Graywater Re-use
In an urban situation, with a utility provided sewage system, we recommend only re-using shower, bath, spa bath and laundry water. Kitchen and lavatory water is best left for the blackwater waste pipe network. Lavatory water is in most cases does not provide enough water to justify the connection cost, and in any case provides additional water flow to help flush the blackwater pipe system.
In a rural situation (i.e. a septic system is used), kitchen water can be used (subject to local regulations), IF the following occurs:
Graywater is called Graywater, Gray Water, Greywater & Greywater. Although debate is still underway (and will probably never cease), the likely outcome is Graywater in the US, and Greywater in other countries. Fortunately most search engines now search for all of the above terms if only one is searched.
Further Information about graywater:
How can graywater be re-used?