Sounds like condensate from the air conditioner - that's where it drains from these cars. Put your fingers in the fluid - brake fluid is thin, oily, and slimy. Betcha this is just water - it may have a little bit of oil mixed in because things can get a bit grimy in the engine compartment.
The brake reservoir is under the hood, directly in front of the driver. Look for the translucent plastic reservoir sitting atop an aluminum pipe with two thin steel lines screwed into it. That's the brake master cylinder & reservoir. It's almost directly over your feet when driving the car.
If you were losing that much brake fluid, I'm pretty sure the brakes wouldn't be working anymore. Plus you'd notice odd behavior, such as the brake pedal going to the floor, but the car not slowing down...