From what I understand, the most important things are the height of the bridge, the depth of the water, how your body is positioned when you enter the water, and the conditions of the water when you hit it (mainly if there are high waves).
You also have to take into account that there's a chance that you don't die on impact, and that you drown or die from hypothermia if you're able to somehow keep yourself afloat. If you somehow survive, you're in for a painful recovery.
I'm reading a book called "The Final Leap: Suicide on the golden gate bridge" and it says
Most people don't know that it's not unusual for jumpers to survive the fall. Upon hitting the water their bones shatter, their body organs burst, they plunge deep beneath the surface, and ultimately they drown. Far from being a fast and painless way to die, jumping from the bridge can produce final minutes that are excruciating and terrifying.
As long as you're okay with that possibility, then just try and make sure you take into account all the variables.