The cheapest thing you did today might turn out to be the most expensive. Ask an AI to write an email and it costs you nothing you can see. Behind that one request, a data center somewhere pulled about a third of a watt-hour of electricity and a small amount of water to cool the machines. Counting the power plant feeding it, a hundred-word AI email runs through roughly a bottle of water, about 519 milliliters, according to researchers at the University of California, Riverside. Now multiply that by a billion requests a day. That is a new kind of industrial demand, and it has to be built, powered, and cooled somewhere real. In Arizona, that somewhere is more and more often the lot down the road, and the data center costs are landing on bills you never agreed to.
The short version
- APS has asked for about a 14 percent residential rate increase, roughly $240 more a year, and a separate increase of about 45 percent for data centers and other large loads.
- The Arizona Attorney General’s expert testimony says the household number could be cut to 3 percent, saving about $524 million a year.
- Data centers are the primary driver of APS’s projected 40 percent peak-load growth by 2031.
- Phoenix-area data centers use about 385 million gallons of water a year, projected to grow tenfold, and up to 85 percent of data center water is lost to evaporation.
- Arizona’s data center tax break costs the state about $38 million a year, and new applications are now paused for three years.
Start with your power bill
Arizona Public Service has asked the Arizona Corporation Commission for about a 14 percent residential rate increase, roughly $240 more a year for an average household. The company says it needs the money because demand is surging: APS expects its peak load to grow up to 40 percent by 2031, with data centers as the primary driver, and it is spending around $2 billion a year on new plants, transmission, and grid upgrades to keep pace.
Here is the line that decides who actually pays. APS is also proposing a separate, much steeper increase for the data centers themselves, about 45 percent, on the argument that the customers driving the demand should cover the cost of serving it. The state’s Residential Utility Consumer Office wants to go further and put data centers in their own customer class entirely. Whether that holds is the whole fight. The Arizona Attorney General intervened in the rate case, the first time a sitting Arizona attorney general has formally opposed a utility rate request, and filed expert testimony arguing the 14 percent could be cut to 3 percent, saving customers about $524 million a year and roughly $220 each, mostly by lowering the guaranteed profit APS is allowed to earn for shareholders. The Attorney General has framed it plainly: the public should not be “subsidizing the cost of building data centers for a whole bunch of out-of-state billionaires.” APS responds that its plan protects everyday customers and makes the big users pay their share. An administrative law judge hears evidence through the summer and recommends a decision around November, with the Commission voting near December and any increase taking effect in early 2027. Until then, whether a data center’s power bill lands on the company or on you is still an open question.
Then the water you can’t see
In a state that has none to spare, water is the quieter cost. A single data center can use anywhere from tens of thousands to millions of gallons a day, and up to 85 percent of it evaporates and never returns to the supply. Phoenix-area data centers already use around 385 million gallons a year, and one analysis projects that growing tenfold. A few cities saw it coming. Chandler caps how much water a data center can draw per square foot, and Marana banned them from using drinking water at all. Most places have no such rule.
Then the taxes you forgot
Since 2013, Arizona has waived sales tax on data center equipment, a break that costs the state about $38 million a year. This June, lawmakers and the governor paused new applications for three years, which tells you how the math was starting to look from the inside. Nationally the trade is steeper still: these breaks can run more than $2 million for every permanent job, and one out-of-state deal handed a data center $77 million in exchange for a single job. The construction work is real and temporary. The permanent payroll is small.
How a data center actually gets approved
So how does a project that reshapes your power bill, your water, and your tax base get the green light? Through four separate doors, and most people never knock on any of them.
The first is the tax break, run by the Arizona Commerce Authority. A company applies, commits to investing at least $50 million within five years, and gets its equipment exempted from sales and use tax for ten to twenty years, under A.R.S. 41-1519. The break is performance-based, you only collect it if you actually build, but it locks in for a long time.
The second is the land, decided locally. Maricopa County now lets data centers go into heavy-industrial zones automatically, with no hearing at all. Anything else needs a rezoning or a special-use permit, which means public hearings at the Planning and Zoning Commission and then a vote by the City Council or the County Board of Supervisors. This is the door where you have the most say: if enough nearby property owners file a written protest, approval can require a three-quarters supermajority instead of a simple majority. It can work, too. In southern Arizona, Pima County voters rejected a data center and then watched the state move to override them. In the by-right industrial zones, that door never opens.
The third is the power, and it splits in two depending on who sends your bill. If you are an APS customer, your utility answers to the elected Corporation Commission, and the rate case deciding all of this is a public proceeding you can read and comment on. If you are an SRP customer, you are in a different system. SRP runs on its own elected board, but the votes are weighted by land ownership, roughly one acre to one vote. The more land you hold, the more say you get. In the 2026 board races, a political committee tied to large energy users ran a slate, and data center companies including Google, which is building a complex in Mesa, and Edgecore donated to it. The renters and quarter-acre homeowners whose bills are on the line barely register a vote.
The fourth is the water, set by cities and the state water department, which can cap use, require a hundred-year supply, or ban drinking water outright. Or not.
Where it helps, where it hurts
None of this is simple villainy, and pretending it is would be its own kind of dishonesty. Data centers bring real capital, real construction work, and a claim to being a serious technology state, the same pull that landed the chip fabs. The tax break only pays out if a company builds. The proposed 45 percent data-center rate and the push for a separate customer class are the system trying, in real time, to make the heavy users carry their own weight.
Where it hurts is quieter. Tens of millions in forgone tax revenue a year for a handful of permanent jobs. Water leaving a drying state for good. And a grid buildout whose bill is being argued over right now, with you as the default payer if the utilities win the argument.
For this piece, APS, SRP, and the Arizona Commerce Authority were asked to address whether data center costs shift to residential customers. Laterstack has also filed public-records requests for the tax-exemption totals, the utilities’ cost-allocation studies, and data center water permits, and will update as those return.
Some cities are starting to organize as a bloc. On June 23, Phoenix joined 42 others in the C40 Cities Global Urban Data Centres Pact, a set of standards that includes data centers paying appropriate rates for the energy, water, and network access they use, with excess revenue directed back into local resilience. Phoenix Mayor Kate Gallego, who co-wrote the launch, named the stakes directly: left unchecked, the buildout could “significantly increase emissions, strain resources, push up residential energy prices and erode public trust,” and cities cannot let “the fear of missing out on new technology result in data centers being waived through our planning processes.”
The door you keep walking past
Which brings it back to the email you asked an AI to write this morning. You paid nothing for it that you could feel. But you are paying for it on your power bill, in your water, and in the taxes that fund the break, and the one cost you actually chose, the query, is the only one that felt free.
The strange part is how much say you have and how rarely anyone uses it. The rate case is open for public comment. The zoning hearings are on the public calendar. The SRP board is elected, even with the deck tilted. The doors are right there, in daylight. Most of us have simply never walked through them. That is exactly how a bill this big gets approved without anyone voting for it.
FAQ
Do data centers raise electricity bills in Arizona?
It is being decided now. APS says large users will pay a separate, higher rate (about 45 percent) so costs do not shift to households, while the Arizona Attorney General’s office argues the proposed 14 percent household increase is too high and could be cut to 3 percent. The Corporation Commission is expected to decide by late 2026.
How much water does an Arizona data center use?
A single data center can use from tens of thousands to millions of gallons a day, and up to 85 percent evaporates. Phoenix-area data centers use about 385 million gallons a year, projected to grow tenfold.
How do data centers get approved in Arizona?
Through four channels: a state sales-tax exemption from the Arizona Commerce Authority, local zoning by a city council or county board, electricity service regulated by the Corporation Commission (for APS) or the elected SRP board, and water approval from cities and the state water department.
How can the public weigh in on data center costs?
By commenting in the APS rate case at the Corporation Commission, speaking at local zoning hearings, and voting in SRP board elections, where votes are weighted by land ownership.
Related Stories
Do data centers raise electricity bills in Arizona?
It is being decided now. APS says large users will pay a separate, higher rate (about 45 percent) so costs do not shift to households, while the Arizona Attorney General’s office argues the proposed 14 percent household increase is too high and could be cut to 3 percent. The Corporation Commission is expected to decide by late 2026.
How much water does an Arizona data center use?
A single data center can use from tens of thousands to millions of gallons a day, and up to 85 percent evaporates. Phoenix-area data centers use about 385 million gallons a year, projected to grow tenfold.
How do data centers get approved in Arizona?
Through four channels: a state sales-tax exemption from the Arizona Commerce Authority, local zoning by a city council or county board, electricity service regulated by the Corporation Commission (for APS) or the elected SRP board, and water approval from cities and the state water department.
How can the public weigh in on data center costs?
By commenting in the APS rate case at the Corporation Commission, speaking at local zoning hearings, and voting in SRP board elections, where votes are weighted by land ownership.