There should be a small hinged opening near the bottom of the machine,normally situated on the right hand side. (this is where the filter is)
Open & behind it you will find a screwed bung.
Unscrew the bung, making sure that you have a container of some sort below to catch the water.
Take care not to let all of the water out in one go as the container will have to be emptied several times to fully empty the machine.
Good luck
Chappaz, October 2009