depends on how long you let it sit after the water wash cycle, with water being heavier then biodiesel, it will eventually settle out but you will always have moisture of some sort. I know there are titration procedures you can do to test for moisture in biodiesel, but they take sometimes hours! If your interested, I will look into them for you, but they may require some special equipment/chemicals. We test moisture with a Karl Fischer unit which is completely designed to test moisture in liquids, but that machine was in the $6000 range.
The only way to be reasonably sure of low moisture without testing equipment, is use a cone bottom tank, put your finished batch in there, and let it sit for a day or 2 then drain off the bottom again.