THE PILOT DRAINED OUT MULTIPLE FUEL TESTER TUBES OF WATER BEFORE DEPARTING ON THE ACCIDENT FLIGHT. SHORTLY AFTER LIFT OFF THE ENGINE EXPERIENCED AN INTERMITTENT LOSS OF POWER. THE PILOT RETURNED TO THE DEPARTURE AIRPORT AND LANDED DOWNWIND, BEYOND MIDFIELD. THE AIRPLANE OVERRAN THE RUNWAY ENVIRONMENT AND COLLIDED WITH THE AIRPORT PERIMETER FENCE. EXAMINATION OF THE WRECKAGE REVEALED CONSIDERABLE WATER REMAINED IN THE FUEL TANKS AND THE OVERWING FUEL CAP SEALS WERE DETERIORATED.