Or just get a water resistant phone. Though I would suggest caution when it's soapy water because that affects the surface tension of the water, which could mean some can slip past the seals that normally keep water out.

Though I have a water resistant phone but have never brought it into the shower with me. It was more of a case of not wanting to be worried about my phone in any kind of a situation involving water. Like going in to one of those 3D movie attractions with moving seats that sprayed water, I was concerned about whether I should be concerned about my phone getting wet. Turned out to be just tiny amounts of water and nothing to be concerned about even if I had my phone out, but after that I wanted to remove that worry from the list entirely.