Comment by Straw

This causes major market distortions and worse outcomes than the econ 101 solution.

The problem is that water isn't traded on a normal market at all. Lots of people have historical water rights and pay nearly nothing for their water use. There's byzantine regulation and many have the right to use for some purpose on their land but not to resell, so the market cannot allocate to more efficient use.

If you just let the 101 level solution actually work, water prices will rise until inefficient uses like water-intensive agriculture (not even all crops!) are pushed out. Urban users easily outbid almost all agricultural use, even at what any person would consider dirt cheap prices. For example, desalinated water, which is considered expensive for agriculture, can be 40 cents per cubic meter of water. That's a lot of water! Usually the last mile of urban water delivery costs more than that.

The amount required to satisfy all urban use, including water hungry lawns etc, and datacenters, corresponds to a very minor reduction in agriculture. Perhaps even just changing which crop is grown or switching irrigation techniques.

Charging more to higher users, price discrimination, causes several problems. First, it creates an incentive to cheat. I'm not using all this water myself, its for this whole group of people who "live" here. Don't allow this kind of spreading (somehow...)? Now you actually screw any business or institution that serves a lot of people. A farm produces food for thousands- do they count as one user? A park uses much more water than a garden but serves many more people. Whatever framework you create will require another bureaucracy to run. Lobbyists will find or insert loopholes for their friends.

The heavy users actually improve the system robustness, in both electricity and water. Their higher demand pays for more supply infrastructure, which itself often benefits from economies of scale, and in a shortage they may even be more responsive to price increases due to their high use.