The pilot reported that during takeoff from a grass airstrip the right main landing gear of the tailwheel equipped airplane came in contact with standing water. The airplane veered to the right, which resulted in the left wingtip striking the ground. The airplane subsequently nosed over and came to rest inverted. The airplane sustained substantial damage to the left wing spar. The pilot reported no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.