Really fun idea, feels like I am actually managing water supply.
Pretty early the biggest bottleneck will become population, which increases really slowly and you can't do much about it. The % of satisfied water supply has no effect on it either, which is a huge missed opportunity to fix exactly this issue in exactly the right time.
The bank loan system gives nice opportunity for the brave to speed up early game, I like that! But then it is basically useless, which is I guess fine. While the interest seems useful with 1% per day, I quickly realized after skimming through the source code that it will give you only 1/384 (1/ingame year) of that per day, making it almost completely worthless. Don't get confused by the FAQ!
The rest is very enjoyable, but lacks content for now. All in all, I think the game deserves 3/5 when considering it as a prototype. But it has potential for 5/5!