The AI water issue is fake

AI data centers use water. Like any other industry that uses water, they require careful planning. If an electric car factory opens near you, that factory may use just as much water as a data center. The factory also requires careful planning. But the idea that either the factory or AI is using an inordinate amount of water that merits any kind of boycott or national attention as a unique serious environmental issue is innumerate. Individual data centers can sometimes stress local water systems in the way other industries do, but when you use AI, you are not contributing to a significant problem for water management compared to most other things you do in your day to day life. On the national, local, and personal level, AI is barely using any water, and unless it grows 50 times faster than forecasts predict, this won’t change. I’m writing from an American context and don’t know as much about other countries. But at least in America, the numbers are clear and decisive.The idea that AI’s water usage is a serious national emergency caught on for three reasons:People get upset at the idea of a physical resource like water being spent on a digital product, especially one they don’t see value in, and don’t factor in just how often this happens everywhere.People haven’t internalized how many other people are using AI. AI’s water use looks ridiculous if you think of it as a small marginal new thing. It looks tiny when you divide it by the hundreds of millions of people using AI every day.People are easily alarmed by contextless large numbers, like the number of gallons of water a data center is using. They compare these large numbers to other regular things they do, not to other normal industries and processes in society. They aren’t aware of how much water society uses on other normal industries.Together, these create the impression that AI water use is a problem. It is not. Regardless of whether you love or hate AI, it is not possible to actually look at the numbers involved without coming to the conclusion that this is a fake problem. This problem’s hyped up for clicks by a lot of scary articles that completely fall apart when you look at the simple easy-to-access facts on the ground. These articles have contributed to establishing fake “common wisdom” among everyday people that AI uses a lot of water.This post is not at all about other issues related to AI, especially the very real problems with electricity use.

I want to give you a complete picture of the issue. I think AI and the national water system are both so wildly interesting that they can be really fun to read about even if you’re not invested in the problem.Importantly, I am not saying that it’s impossible for data centers to ever cause any problems with water. They require careful planning in the same ways other large industrial buildings do. What I am saying is that right now no reasonable forecasts imply that data centers will rise to become a significant problem for water access in the US. Almost all complaints about their national water use are basically just saying “We should not have a new large industry in America using water.” The tax revenue per gallon from data centers is just so high that in many places they are among the best new buildings possible to benefit a community experiencing water scarcity, because any other industries using the same amount of water would generate way less tax revenue. Critics of data centers need to carefully weigh their water costs against the massive amounts of revenue they can bring in for everyday people, not just look at the water costs alone. The debate about building data centers should involve reasonable conversations between ecologists, economists, and city officials, not everyday voters shouting down local meetings with misleading statistics.A few important definitionsAI water use isn’t an issue on the national, local, or personal levelNationalLocalPersonalHow big of a deal is it that data centers use potable water?Do data centers poison water supplies?Using AI can save way more water than is used in data centersIt’s okay to use water on a digital productThe social value or harm of a tool isn’t the final word on how harmful it is to the environmentThere’s a trade-off between water and energy for data center cooling systems. For the climate, water’s often preferableWhat about all those news stories about AI harming local water access?Every popular article about how AI’s water use is bad for the environment in the last year has had a wildly misleading framing5 common misleading ways of reporting AI water usage statisticsSome examples of great news coverageFurther readingSuppose I take a cup of water from a lake, and then immediately dump it back in. That doesn’t seem bad. Now I take a cup from the lake, and this time I evaporate it. That seems worse. Now I take a cup and spend some resources on making it drinkable. These all have very different costs and effects on the water system.

We need words to describe it.Water is complicated, but not too complicated. There are a few key definitions to understand. First:Consumptive use removes water from a local system. Taking the cup of water and evaporating it is consumptive use. Evaporated water mostly does not return to its original source.Non-consumptive use temporarily takes water from a local system, and returns it later unaffected. Taking the cup of water from the stream and pouring it back in is non-consumptive use.Growing food is an example of consumptive use. Some of the water becomes part of the food itself. When the food is shipped away, the water leaves the local system.Many data centers rely on evaporative cooling. This is the way water is consumptively used in data centers. They do not immediately evaporate all the water they are using. Most of it circulates through the cooling system repeatedly before evaporation.Many reports on AI’s water use do not only include water in data centers, they also include the water consumed by the power plants data centers draw from. This leads to a second important distinction:Direct use: The water used inside AI data centers themselves to cool servers.Indirect use: The water used in nearby power plants to generate electricity the data center uses.The U.S. electricity sector uses approximately 50 trillion gallons of water each year — enough to cover all of Pennsylvania in five feet of water. However, most of that use is non-consumptive.The average kilowatt-hour takes 4.35 L (1.15 gallons) of water to generate. Unless electricity is sourced entirely from wind and solar, most activities have an indirect water cost. A digital clock has a direct water cost of zero, but an indirect water cost of 0.2 L of water per day. Every three days, the clock accounts for a bottle of water’s worth of consumption at a nearby power plant.It is standard practice in environmental reporting on AI to include both onsite and offsite water usage. On average, the water data centers use to cool servers is only about one-fifth of the water required to generate the electricity the servers use. Put another way, almost all (80%) the reported water used by AI occurs during the generation of electricity. Data centers primarily consume water indirectly, similar to any other industry.Consumptive use can harm total access to freshwater, but freshwater sources are also regularly being replenished.

The full balance of and access to freshwater is beyond the scope of this report. The key takeaway is that evaporating freshwater removes it from the local supply, although new freshwater is added elsewhere. There is ongoing debate regarding the severity of this issue for total U.S. freshwater supplies. The U.S. has more abundant and cheap freshwater than most other countries.Another key definition is potable water: freshwater treated enough that it’s safe for human consumption. It’s not actually very costly to turn freshwater potable. It’s much more costly to turn saltwater potable. Most water used in physical data centers themselves is potable, because it needs to be very clean to flow through the cooling systems without harming the pipes.So of the ways AI uses water:The vast majority (maybe 90%) is withdrawn, freshwater (not potable) that is indirectly (offsite) used non-consumptively in power plants (it’s returned to the source unaffected)Less (maybe 7%) is withdrawn freshwater (not potable) that is consumed (evaporated) indirectly (offsite) in the power plants to generate the electricity AI uses.And less (maybe 3%) is withdrawn freshwater that’s then treated to become potable, used directly (onsite) in physical data centers themselves, and consumed after (not returned to the source, evaporated).This post is mainly going to focus on the ways AI causes water consumption, not non consumptive withdrawals, because removing water from a source is a significantly bigger problem than temporarily using it and then returning it unaffected.There are a lot more terms in water management, but these are most of what you need to understand the issue. Another key point is that data centers don’t meaningfully pollute the water they use, so terminology around pollution doesn’t come up.Finally, it is important to note that most activities consume water. Most U.S. electricity is generated by heating water to spin turbines. Water is used in the production of most physical objects. The majority of the average person’s consumptive water footprint stems from food consumption. Domestic water use accounts for less than 8% of an American’s daily footprint. An American’s total consumptive water footprint is approximately 422 gallons of fresh water per day.All U.S. data centers (which mostly support the internet, not AI) used 200–250 million gallons of freshwater daily in 2023.

The U.S. consumes approximately 132 billion gallons of freshwater daily.1 The U.S. circulates a lot more water day to day, but to be extra conservative I’ll stick to this measure of its consumptive use, see here for a breakdown of how the U.S. uses water. So data centers in the U.S. consumed approximately 0.2% of the nation’s freshwater in 2023. I repeat this point a lot, but Americans spend half their waking lives online. A data center is just a big computer that hosts the things you do online. Everything we do online interacts with and uses energy and water in data centers. When you’re online, you’re using a data center as you would a personal computer. It’s a miracle that something we spend 50% of our time using only consumes 0.2% of our water.However, the water that was actually used onsite in data centers was only 50 million gallons per day, the rest was used to generate electricity offsite. Most electricity is generated by heating water to spin turbines, so when data centers use electricity, they also use water. Only 0.04% of America’s freshwater in 2023 was consumed inside data centers themselves. This is 3% of the water consumed by the American golf industry. How much of this is AI? AI uses approximately 20% of the electricity in data centers, though this is obviously forecast to increase significantly. Water use roughly correlates with electricity, because offsite water is used exclusively for generating the electricity data centers use, and onsite water is used to cool chips after electricity flows through them and heats them up. For now I’ll assume AI also uses 20% of the total water data centers use, with large error bars.So AI consumes approximately 0.04% of America’s freshwater if you include onsite and offsite use, and only 0.008% if you include just the water in data centers.