It's hard to drown in a bathtub. Hitting your head and hyperventilating doesn't get rid of your SI. What if hyperventilating causes you to pass out? Chances are then that your head isn't going to go under water because it's freaking hard to drown in a bathtub. How long are bathtubs? Five feet or less? Your legs will keep you from going down low enough for your head to be covered by water. And I agree with the other poster about inflicting an injury on the back of your head. if you can hit yourself hard ONCE and cause bleeding, then maybe. Once you hit yourself twice, though, the jig is up, if you happen to have this method end successfully. And you better make damn sure that someone else can't be blamed for murder somehow! A murder and an "accident" like this look very similar. Has to be a simpler way. This seems complicated to me for some reason. And if you do any searching on your device for "methods" to make a suicide look like an accident, you are leaving tracks, even if you wipe your phone. and don't forget about the insurance companies who will certainly do their own investigation. Who knows if it will work as far as being detrmined an accident. One thing is for sure; if you are successful, you will never know if your plan was successful.