I know we've heard this before but here is a first-hand story, at least
for me.

A friend writes:

Phone didn't work, even though battery had substantial charge.

At the T-Mobile service center, the rep opened the phone and showed me
that it was wet inside. Why? When I turned on the water at the
fountain, there was a surge that thoroughly doused my pants and sport
jacket. Even though the phone was in my shirt pocket underneath the
jacket and was partially protected by a rubberized case. enough water
managed to seep in to cause the phone to malfunction. The rep suggested
that before I opted for a replacement phone, I should disassemble the
phone (basically taking the battery and SIM card out) and immerse it in
bowl of uncooked rice for 24 hours. It worked! I mentioned this to a
number of people who were aware of this "folk remedy”. Silica gel would
even be better as a desiccant, but it is not exactly a household item.