I have put mine through the dishwasher. Top shelf, no heat. I think you need to know your dishwasher. I did find that the motor became hard to take out after that but a little petroleum jelly around the gasket helped made it easier.
I find though that it is just as easy to wash by hand if I keep up with it weekly.
I used the dishwasher for the main 2 big parts a few times. Top rack only, and turn off the hot dry. I hand washed everything else. Usually I just hand wash everything. I soak them in hot soapy water, and a little bleach. If I leave them in there a while, it washes up really well (usually I forget I was cleaning it and come back an hour later
I have the Drinkwell Platinum and it didn't survive the dishwasher. The uptake section warped so that it wouldn't fit the bottom. The company did send me a new part free of charge, because they do state that it's dishwasher safe. I hate cleaning the thing (just did my weekly cleaning today) but I hated having to fill up water bowls every night, too. And my cats drink much more water with the fountain so that makes mama happy.