It is a flaw. I had the same thing on the hybrid I used to have. I added a support in the middle and also another going across the bottom of the tank from support to support. I couldn't get all of the water but it got me a few more gallons. My biggest problem was getting all the antifreeze out of the tank. My quick fix for that was to use a 1 x 4 board. I could squeeze one end of it up between the support and tank on the end away from the pump pick-up or the drain. Then slide the board under the tank until the other end went under the other support. This lifted the belly of the tank so more water/antifreeze would come out. Do not drive with the board in there unless you find a way to secure it. This is what I did until I got another support made and installed.