The pilot of the tailwheel equipped airplane reported that he touched down in the grass adjacent to the paved runway. During the landing roll, the airplane encountered a low spot in the runway with about 3 to 4 inches of standing water. The wheels dug into the terrain and the airplane nosed over coming to rest inverted. The airplane sustained substantial damage to the rudder, horizontal stabilizer, and left wing strut.

The pilot reported no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

The pilot reported that he should make it standard practice to make an inspection pass of the runway whenever he is landing on turf to determine the condition of the runway.