Hi Earl. The Kimberley is worth looking at if you want a grey water tank. They are made in northern NSW. http://www.kimberleykampers.com/
Most of Australia has low population levels and therefore has a lot more "bush" than many other countries. Consequently, there is less need to carry away grey water. The main exception is in some National Parks that are in environmentally sensitive areas.
Personally I own a Kedron ATV off road caravan. Kedron are made in Brisbane. If you wanted a grey water tank and you are buying a new caravan, almost any manufacturer would do it for you. You just have to ask and then cough up the money.
Right now in Sydney the Caravan and Camping Supershow is on at Rosehill Race Course. Good opportunity to see all the players in one place.
Clyde Camel.
-- Edited by Clyde Camel on Monday 23rd of April 2012 11:01:25 PM
Earl welcome to the site. We are starting a 2 yr trip around Oz, and have purchased a Montana 21ft Archer Offroad Van, from Adventure Caravans at Loganholm. Adventure give fantastic after sales service, have heard some horror stories lately about after sales service. Montana are not priced over the moon but are solidly made. Some advice i read here or elsewhere was find a dealer you feel comfortable with. We are currently back in NZ and Adventure are baby sitting the van for us. Fly back 11th May. You are welcome to view it then if you wish.