On April 12, 2017, about 1115 central daylight time, a Cessna 152 airplane, N95551, was substantially damaged when it nosed over following a forced landing at the La Porte Municipal Airport (T41), La Porte, Texas. The commercial pilot was not injured. The post-maintenance test flight was conducted under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed. The local flight departed about 1150. According to the written statement submitted by the pilot, during a low approach to the runway, "there was a noticeable lag in the response of the engine " and the engine lost power. The pilot attempted to restore power but was unsuccessful. There was no remaining runway so the pilot turned the airplane to avoid a ditch. During the landing the airplane encountered soft ground and the nose wheel dug into the ground. The airplane nosed over resulting in substantial damage to the empennage and firewall. The airframe and engine examination revealed water contamination in the engine's fuel lines, fuel bowl, and carburetor. No water contamination was noted in either of the fuel tanks. An examination of the engine and fuel system revealed no mechanical anomalies that would have precluded normal operations. The pilot wrote that the preflight inspection did not show any evidence of water when samples from the main fuel tanks were taken. During the preflight run-up the engine ran without hesitation or sputtering.