There are three types of water in a home: White which is purified water, black which is sewage water and grey which is in between.
Greywater usually comes from use in bathroom sinks and showers as well as the kitchen sink and clothes washer. These are commonly referred to as fixtures. The most economical way to use the greywater from your home is for use in nearby irrigation outside the home that is in close proximity to each of the fixtures. The greywater is gravity fed to the landscape areas so the use of pumps are not required.
As with any system, there are many ways to use greywater other than mentioned above but with each comes additional cost. Irrigation with use of a storage tank and pump. One can use this with and without a purification process. Without purification, one can only store the greywater for 24 hours without the build up of bacteria that can negatively affect the water. Purification is very expensive and hard to come by for residences so for now it is best to use it for toilet flushing (with use of a cleansing tank and control system) and immediate irrigation (instant release of the grey water to the landscape).