Witnesses heard the engine sputter after takeoff as the aircraft was in a steep climb. The aircraft was then observed to turn sharply left, enter a nose down attitude, and crash. About 1/2 teaspoon of rusty water was found in the main fuel strainer and the fuel screen contained rust. About 1/2 ounce of contaminated water was found in the carburetor bowl. The aircraft had been refueled the week prior to the accident at Albert Ellis Airport where the FBO had been out of fuel the previous 45 days on 5 or 6 different occasions. Two other aircraft also reported receiving contaminated fuel from the FBO. The fuel filters on the fuel truck and at the fuel farm were out of date. The day the aircraft was refueled, the fuel truck took on a load of fuel at the farm at the same time a fuel tanker truck was off-loading fuel into the farm. The aircraft fuselage tank does not have a quick drain. The engine performed normally during a subsequent operational check.