The windscreen washer resiviour is located behind the front bumper on the right side of the car. The washer bottle has two washer motors in the bottle either of which could be leaking from the rubber grommet that seals the motor to the washer bottle. Do you see a puddle of washer fluid under your car or does the bottle only leak if the bottle is over half full? Gaining access to the washer bottle may require removing the front bumper. I would phone around and see if there are any independent BMW repair shops i n your area.
i do not see fluid coming out. It takes a month for it to leak out and I was told that it was in the line that sprays fluid onto the headlights. I did not know that it did this and do not think it actually does. However, there is a line that appears to be connecting in that area.