That is wildly inaccurate. Unless you live in Texas (because they were stupid enough to change this) your local public service commission sets the rates you pay for electricity. They do this based on operating costs and planning. There is no "demand-based" increase in costs, in part because this is one of the reasons they're a public utility--so the people don't get priced out of something considered essential or squeezed dry by capitalism run amok in a monopoly market. It's highly unlikely that anywhere has a PSC so horrible at their jobs that an upgrade to infrastructure is going to result in a significant increase to customer costs for more than the time it takes to burn off the one-time cost of infrastructure upgrades, and they should already be budgeting for upgrades because their human customers just keep having sex. It's been going on for quite a while.
Claiming the cost of water has "only recently" become relevant is simply disingenuous. Partly because in excess of 80% of data centers use closed loop glycol systems that need refilling far less often than the radiator in your car. It takes substantially less water than goes a small swimming pool to fill them, and once they're filled there's no more water "use". By and large it's only the poorly designed sloperators (which should probably just be made illegal) that are using evaporative cooling, so the actual reason "the impact of water over-use was an external cost" was that the toilets and the break room sinks don't use enough water to matter, and the rest of the system would be hard-pressed to lose more water in a year than flushing all the toilets once.