Do data centers use a lot of water? That’s what I kept hearing in the news. And as a swimmer and a beach lover, I definitely wanted to understand whether that was true.
There are two common complaints about data centers and water. One is that they always use massive amounts of water and deplete the local water supply. The second is that data centers by default release contaminated water back into the local watershed. I’ve learned that neither of these is necessarily true.
There’s variation to how data center projects handle their water usage, and some are admittedly more reliant on water than others. But the outliers don’t define the entire sector. It’s in the best interest of both data center operators and the communities they serve to use cooling methods that are appropriate for their specific location. First, let’s learn more about why data centers need water in the first place.
How Do Data Centers Use Water?
I’ll admit that I didn’t fully understand why a data center really needed water. Isn’t it basically just a warehouse? But I get it now: the main thing a data center usually needs water for is cooling.
You might remember that a data center is a secure building that holds computers called servers and other network equipment. Like your phone, laptop, or other electronic devices, those computers generate heat when they run. If you’ve ever had to pull your car over when its engine got too hot, you’ll understand why that heat can be a bad thing. Each individual computer needs to be kept within its normal operating temperature, as getting hot slows down processing. And, with shelves upon shelves of these computers running at the same time and releasing heat, the surrounding room needs to be kept cool, too.
You might wonder why we don’t build all data centers somewhere very cold like Antarctica, since they need to be kept cool. That’s because digital services work best when they are near the people and businesses that are using them.
So given that data centers need to be in the same types of places where humans can live comfortably, that takes us back to the challenge of keeping everything cool so that it runs smoothly. There are several different methods of data center cooling that each have a different impact on the amount of water a data center needs.
Different Types of Cooling Systems
There are several main approaches to data center cooling that can be used in different combinations depending on the resources available in a location.
- Traditional air cooling (basically air conditioning) uses fans to move artificially cooled air around. This doesn’t require water, but it does require more electrical power. Once a data center gets large enough, air cooling may not be the most energy efficient option.
- Evaporative cooling lowers air temperature by evaporating water. This is the same way the human body cools down, through the evaporation of sweat off our skin. This is where much of the “bad press” about data centers’ high water consumption has come from and why newly built data centers increasingly use other cooling methods.
- Closed-loop cooling is one of the most common cooling methods for purpose-built data centers (that is, buildings that were intended to be data centers from the beginning and were optimized for that purpose, as opposed to buildings that used to be something else and were turned into data centers). In closed-loop cooling, the system is filled with water once at the time of construction, and that same water recirculates constantly through pipes that remove heated air.
- Newer innovations like direct-to-chip cooling and immersion cooling are becoming more common with higher-density data centers. Both of these methods use coolant to remove heat from its source, the computer itself, meaning that not as much heat is released into the air inside the data center, thereby placing less demand on the building’s cooling system.
What happens to the heat after it leaves the servers can also affect a data center’s need for water.
- Dry coolers use fans and outdoor air to reject heat and require little or no water consumption.
- Cooling towers use evaporation to reject heat but use water during the process.
- Hybrid systems use a combination of these approaches, operating mostly without water but switching to evaporation during hot periods when more cooling is needed.
There are tradeoffs for different methods of cooling. As I mentioned, air cooling uses no water but more electricity. Closed-loop cooling uses the same water repeatedly, but there may be evaporation from the cooling tower depending on how it’s designed. Responsible developers consider the surrounding environment when they select a method for a given facility. In water-constrained areas that have plenty of power available, air cooling might be the right choice. Yet in an area that has abundant water, using less electricity but some water might be better. Data center cooling is not a one-size-fits-all approach, so it’s important for community members to ask questions and understand the project and the needs for their location.
Do Data Centers Impact Local Water Resources?
Aside from cooling, data centers only use water in the same ways as any normal commercial building: for things like restrooms, sinks, landscape irrigation, and occasional system maintenance. As long as a data center is designed to match local needs, it will not impact local water resources any more than another office building of a similar size.
In a closed-loop system, water from the local supply may be used for the initial filling of the system. The exact amount of water needed varies depending on the size of the facility. Once the system is filled, that same water is used again and again and only needs to be topped off very occasionally, like in a swimming pool. The water is supplemented with a coolant like propylene glycol, which is a completely safe additive found in many everyday items including cosmetics, food, and medicine. The mixture stays inside sealed piping. It is not discharged into soil, groundwater, waterways, or the public water system. If the system ever needs to be drained for maintenance, which is rare, the fluid is captured and handled according to applicable environmental requirements.
Summing It Up
Any responsible data center operator can be expected to comply with all applicable water, wastewater, stormwater, and environmental requirements. It is reasonable for communities where data centers operate to ask questions about water usage and to hold operators to a high standard. While specific permits and safeguards will vary by site, the goal is consistent: use water responsibly and protect surrounding ecosystems. After all, why would a data center operator want to deplete a resource that they rely on as much as we do?
Understanding data centers starts with understanding the role they play in everyday life. Explore the rest of our Data Centers 101 series to learn how these facilities are designed, operated, and integrated into the communities they serve.
- Source data (links) for water usage. Lawn irrigation / residential outdoor use: ~2,920 billion gal/yr, corn irrigation: ~2,820 billion gal/yr, alfalfa irrigation: ~2,820 billion gal/yr, almond irrigation: ~1,600 billion gal/yr, golf courses: ~531 billion gal/yr, meat & poultry processing: ~150 billion gal/yr, paper & pulp mills: ~175 billion gal/yr, food & beverage manufacturing: ~150 billion gal/yr, pharmaceutical manufacturing: ~97 billion gal/yr, avocado irrigation: ~60 billion gal/yr, dairy processing: ~56 billion gal/yr, breweries: ~32–43 billion gal/yr, oil refining: ~22 billion gal/yr, all U.S. data centers: ~17.4 billion gal/yr ↩︎
