Hang the reborn upside down and get endless water because their lungs will never fill.
You could build a campaign around that. Some village in an oasis is just torturing some reborn they caught and use the endless water to feed the well. Get enough water and there could be some climate change.
Many years ago I was in a 3e campaign set in Dark Sun. My character wound up with an everflowing water bottle off of a random table. After the campaign was over, he retired by using it to make a giant pond which he sold access to. It nearly destroyed the economy.
Maybe have the reborn die mid-campaign and they are experimenting on people to try to get their water back.
With enough flow the throat could be overwhelmed, filling faster than it empties. Bonus damage from literally having an explosion of water inside your lungs.
Oh no, it's salt water!
Meh, I dont wanna be a DM that stops creativity.
slorp slorp slorp
Now THIS is a real Swiss Army Man.
