We can point at Meteor man to establish that realism might not apply because it is an example of where the fiction diverged from realism. Hence it might diverge from realism in another spot. We weren't warned before hand for Meteor Man so we don't have to be warned before hand for water in the lungs. It is fiction. It can be anything the author wants because the authority on those internal rules is the author.
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I don't think she expected it. There is also a case where Tolkien had "one of the gods" save an elf by having a wave rescue only that elf and carry it all the way to land. So she might have hoped she would have divine help but I don't think it is the case that she knew.