It’s an interesting read. I see well thought out concepts and characters and glimpses of a vast world that runs on riverwater. An unusual choice for sure. But it gives all the abilities an interesting handicap, as they first need to drink the water to be able to do anything “special.”
The very first chapter had a few especially strong and clear images, and I see that strong writing again and again during the novel, but there are also moments that feel rushed. Where detail is missing and there are some things that come across as logical errors, probably because the writing could have gotten a bit more polish. Which is actually hard in the rather short time frame the ISEKAI contest had.
Shoving these caveats out of the way, I want to encourage the writer to keep writing. You will get even better with time and I am sure you’ll craft something really great in the future.