EE was backing water truck & misdirected the truck into a berm at a sharp angle. Truck was full of water & with R-rear wheels up on berm rolled over to left & settled upside down on access road a few feet below. EE was using seatbelt. EE was evaluated by ER on 5/1 & by Occ Med MD on 5/2 and given full release; On 5/12, eval by Occ Med MD resulted in TTD.