what were the symptoms that led you to believe it was the water pump?
While driving on the freeway the yellow temp light and chime came on followed quickly by the red light and chime. Also the fan had been louder than usual for a couple days but I hadn't had time to investigate. When i pulled over and opened the hood coolant had sprayed everywhere. The car would start and run but I only drove from the driveway (where the tow truck driver set it down) into the garage, 30-40 feet max.
Btw, my car is an '06 330i with 130,000 miles.