On July 17, 1996, about 1845 eastern daylight time, a Piper PA-18, N7168K, collided with trees and the ground, following a loss of engine power during cruise flight. The airplane was operated by the owner/pilot under the provisions of Title 14 Part 91, and visual flight rules. A flight plan was not filed for the personal flight. The commercial pilot was not injured, and the airplane was substantially damaged. Origination of the flight was Gatesville, North Carolina, about five minutes prior to the accident. The pilot reported that the float equipped airplane departed from a canal in Gatesville. He was flying locally to a river about five miles from the canal. After take off, the pilot turned toward the river, over flying a swamp adjacent to the canal. After less than five minutes of flight, the engine sputtered and quit. Since the flight was cruising about 500 feet above the ground, according to the pilot, there was little time to respond, and he did not apply carburetor heat. The ambient conditions were conducive to carburetor icing. The pilot also stated that he had extended range fuel tanks with flush mounted fuel filler caps, and had previously had problems with water in the fuel tanks, particularly following rain. There had been recent rains because of a local hurricane. According to the pilot's report, he subsequently examined the fuel system and found water in the gascolator, and in the fuel line between the gascolator and the carburetor. He also reported that of four spark plugs removed for examination, two were black and two were clean.