If it was possible to own the water and then sell the rights to it the markets and price signals would make conservation work. But no. We have to collectivize it.
What's also really interesting is that Native reservations often have the worst shortages because they aren't allowed to control or sell the water on their land. https://perc.org/2022/02/14/addressing-institutional-barriers-to-native-american-water-marketing/
There's some really fascinating research on this published by the Property and Environment Research Center (PERC) if you want to give it a look.