It may only work for a while if water does not penetrate the sensitive components of the phone. I can assure you that your iPhone will not fix itself and that your situation will experience other problems progressively or even instantly. In case your device sinks, here are some tips you should know to get water out of your phone. While it can remove some of the moisture from the surface, it will do very little to remove moisture from the inside of the device, and the heat could irreparably damage the phone's internal components.
So what's the best way to protect your phone from liquid damage? Asurion experts get asked this question frequently and they help our 300 million (and counting) customers with all their technical support needs.