The vetiver network is a really fantastic web environment.. you can find and ask everything you're searching about this plant species and his application for water treatment.
http://www.vetiver.org/discus/messages/16/16.html and there are at least 30 discussion links related to vetiver and water purification such us for example.
- Effluent pond treatment using vetiver grass: http://www.vetiver.org/discus/messages/16/778.html?1255777325
- Basic household system: http://www.vetiver.org/discus/messages/16/1057.html?1211996863
-Vetiver for Sewage treatment in Australi:a http://www.vetiver.org/discus/messages/16/492.html?1141668160
... and many others!!!