I wouldn't even try plugging it in after being submerged in water for 5 hours. It's just not worth it.
You don't specifically need an Apple power adapter. The USB-A Apple power adapters are ordinary "dumb" power supplies and I've used good quality aftermarket USB power adapters without any problems. If you want to get an Apple replacement, the 12W versions that come with iPads are fully compatible and cost the same as the 5W iPhone power adapter. They will charge at the maximum rate unless you have an iPhone 8/8+/X, which can charge even faster with a USB-C power adapter.
Apple 12W USB Power Adapter - Apple
I don't know if you're in the United States, but you should be able to find the one sold in your area if you're not.