Share your experience!
The trouble is that most or almost all will not have closed the flaps correctly and then the rest jump on the band wagon and say the same thing - If you have ever seen these phones then you will see that this was user error hence warranty void but by all means take it to the place of purchase or contact Xperia care to arrange a water test via a service centre http://www.sonymobile.com/global-en/support/contact-us/
They maybe able to direct you to the nearest service centre
or I've heard members recording a water test to prove that any damage incurred isn't due to misuse but should you choose to record you will have to show the phone working before submerging it, However this can be misconstrued as the damage may occur after recording from misuse and you could claim it was not apparent after a water test