How much water would you need to put out the sun?

The sun is a giant ball of gas that burns at the centre of the solar system. And the adjective giant is not unearned: the sun constitutes 99.86% of the mass of the solar system. Without it life as we know it would not exist. Water would not be liquid. Plants would not be able to photosynthesise. Without the sun the earth would just be a big icy rock floating through interstellar space. But let’s assume you have a death wish and want to try to put it out. How much water would you need?