In the USA it is common ...
Published by Rodney Ruskin, Geoflow, Inc. - C.E.O.
In the USA it is common practice to filter grey water to 120 microns and use it with landscape turf or trees with subsurface drip irrigation. This is low cost combined with low risk. To read about this technolgy please go to: http://geoflow.com/research_w.html . If you are interested I will introduce you to a supplier in India.
Rodney