Because you don't pay for the water, you buy the rights. Water is treated like an infinite source with a limited flow rate, and the source itself is sold as property.

The solution is not to price water as a commodity, either. If we priced water high enough to disincentivize waste, we would create an incredible burden for regular people. Water should be as cheap as possible, and at the same time regulated to guarantee an amount of conservation. People who can afford to more than double a state's power grid capacity, all for a single data center, can afford more water than the populace can afford.

What we need is to regulate water use generally so that the watersheds and ecosystems we rely on can be reasonably conserved.