PSA: your phone is not waterproof and won't be water resistant forever
This wasn't a good thing. Although the phone still looked fine to the naked eye, it had most likely lost its water-resistant properties. Its out-of-the-box IP68 rating couldn't be trusted anymore. This is what inspired me to write this quick post explaining why today's phones are not completely waterproof, and even those IP68 water-resistant ones won't be immune to water damage forever.
Waterproof vs water resistant: what's the difference?
If you look at the specs sheets of today's top smartphones, you'll notice that most of them have a water and dust resistance rating of some kind, most commonly IP67 or IP68 (pronounced "IP six seven" or "IP six eight"). This is also known as an International Protection Marking code. The first digit indicates a level of dust ingress protection, while the second digit tells us how hard it is for water to get inside. The higher the digit, the better protected that device is.
What you're less likely to notice is that none of these phones are advertised as waterproof. They're merely water resistant, not entirely immune to liquids. In other words, even a phone with a rating of IP68 – the highest you'll find on a typical phone – may incur water damage under certain conditions. It will survive a drop in the toilet, but probably not being sprayed by a jet of hot water (a requirement for obtaining an IP69 rating, by the way).
And why may water protection fail?
If you go to the Apple web site and scroll down to the very bottom of the iPhone XS product page, you'll find the following disclaimer: "iPhone XS and iPhone XS Max are splash, water, and dust resistant and were tested under controlled laboratory conditions with a rating of IP68 under IEC standard 60529 (maximum depth of 2 meters up to 30 minutes). Splash, water, and dust resistance are not permanent conditions and resistance might decrease as a result of normal wear."
This applies to not only iPhones. Practically every water-resistant phone may lose its ingress protection over time, simply because it is being actively used. Accidental drops, exposure to extreme temperatures, and contact with salt water may cause adhesives to loosen. Dust particles that end up behind your speaker grill may penetrate the speaker driver's membrane and insulation. And if you crack your phone's screen or glass back, its water resistance is pretty much done with. Currently, no major brand will honor your phone's warranty if evidence of water damage is present.
What can I do to keep my phone safe?
Your phone is protected against water not because its maker wants you to go scuba diving with it. Its IP rating is there to ensure that rain droplets or accidental spills won't damage your 1000-dollar gadget. That said, not submerging your phone underwater would be a good idea (although I do admit that I've done it several times – while taking the necessary precautions). And if it does get seriously wet, be sure to promptly wipe all moisture off with a dry towel. Do not use a hairdryer. Needless to say, never attempt to charge a wet phone as droplets in the charging port may cause all sorts of damage. And be sure that the protective rubber seal on its SIM card tray is in good condition.