My phone never got wet. One day I tried to charge my phone after it died, and it wouldn t charge. I thought it was my charger, it didn't say anything about water being detected, so I used the one at work and it did the same thing. I left it plugged in and at the end of my shift it had fully charged. Now it just says there's water detected. I tried drying it several ways and nothings working. I'm positive that my phone and the charger are dry.
Read more: https://samsungus.org/qa/s9/samsung-galaxy-s9-plus-water-detected.html