A/C condensation drain

I recentley picked up a used 98 passat. When I run the A/C within an hour or so it starts to rain inside the car from condensation pouring out the air vents. There is so much water that the floor, mainly on the passenger side, is soaked. You can see the water sloshing on the floor when you acceleratee and brake. I would venture to believe that there is a drain somewhere that is full of debris. Can anyone tell me where the drain is located and if I could clear it myself or should I take it in.