Sarah over at Sarah's Bearded Dragon Rescue (a great blog about nursing sickly/neglected beardies and some other lizards back to health) has successfully trained her beardies to drink from their water bowls.
I trained mine to do this as well. Started with drinking in the bath then progressed to bowls. I stopped this immediately after my female aspirated and died in my hands. I was able to bring her back successfully with cpr, but I was very lucky. I will never take the risk again, and would advise others against it. The panic I felt was indescribable.