In addition to the water consumed by data centers, Boritt and other environmentalists bring up concerns surrounding the water that is left over.
Certain chemicals must be added to the water used by data centers for various reasons. Biocides are added to prevent mold, algal or bacterial growth. Phosphates may be added so that the water doesn’t lead to corrosion.
Unintentionally, that water could also pick up traces of heavy metals like zinc, copper or lead as it comes in contact with the metal components within data centers, which naturally degrade. There is also the potential for water to pick up contaminants like PFAS. And as water evaporates during the cooling process, these pollutants become increasingly more concentrated.
What happens to the contaminated water?
That contaminated water has two pathways it can theoretically take.
If a data center holds an NPDES permit, it can discharge certain pollutants into a waterway under certain circumstances and within specific limitations depending on the pollutant, although these are not always followed. In 2018, the Environmental Protection Agency (EPA) found that 20.3% of facilities with NPDES permits were in “significant noncompliance.” That could be discharging more pollutants than permitted or failing to report information that could reveal deficiencies in these discharges. The EPA successfully reduced that to 9.3% in violations in 2023.
Data centers may also perform treatment on site to cleanse that water.
Boritt is concerned that the water from data centers may be overly clean when it is discharged into the state’s waterways, treated with chemicals that prevent the growth of aquatic life and lacking the nutrients that support it. As a result, gallons of ultra clean water could enter, and consequently disrupt, aquatic ecosystems.
Water picks up various nutrients as it moves through the water cycle, Boritt said. It falls onto the landscape, filters through substrates such as soil or wetlands, or is held in leaf litter on the forest floor. The natural minerals and biomatter that it picks up can be critical to aquatic life. The water data centers discharge is unlikely to contain this matter.
“You have the potential to create these biologically dead areas because the water can’t sustain life,” Boritt said, comparing the situation to adding tap water to a fish tank.
Even in small quantities, if this water affects the macroinvertebrates (tiny, aquatic larval insects that indicate the biological conditions of water) the effects can ripple, moving up the food chain through various consumer species. Boritt said this could eventually affect species like eastern hellbenders, bald eagles, ospreys and great blue herons, to name a few.
He compares it to a kind of opposite of the deceased Rachel Carson’s “Silent Spring,” a book written about the environmental catastrophe that DDT and other pesticides created. The reverse could be environments too clean to support life rather than too polluted.
Water temperature also comes into play. The evaporative cooling process heats up the water and, if directly discharged, it is still at a temperature warmer than the waterway it enters. Aquatic organisms are sensitive to temperature changes, and discharging warm water can promote the growth of harmful algae blooms, which can emit toxins dangerous to humans, plants and animals.
If water is not directly discharged from a data center, it would take the same path that all water from housing, business and industry takes: to wastewater treatment plants, which clean the water before discharging it back into the environment—usually rivers.
The worries with wastewater treatment plants
Todd Royer, an aquatic ecologist at Indiana University Bloomington, says the concern there is the sheer volume of water that data centers could contribute to wastewater treatment plants. The question is: Can wastewater treatment plants handle this rapid influx? All on top of the state’s residential development, which adds to the volume these plants will be expected to treat?
Royer said this question isn’t anything new. With every new industry or housing addition, there is always the question of if wastewater treatment plants can handle an influx in water. However, there is a lot of ambiguity about the exact amount of water that data centers send to wastewater treatment plants.
The EPA has set standards for the water discharged from these plants. Royer said that in some situations, the water expelled from water treatment plants, as when the data centers do it, could be cleaner than the river or stream it is discharged in—this may especially be true for Indiana, with the state consistently facing water pollution issues.
It is also notable that the water coming from data centers is different from the water that would come from housing divisions or industries. The chemicals or minerals that Royer said are often cause for concern in aquatic ecosystems are nitrogen or phosphorus (which primarily originate from the agriculture industry). What Royer said are frequently known as “personal care products”—things that individuals choose to use—can also have adverse affects on ecosystems.
The latter are frequently unregulated—things like caffeine, pharmaceutical compounds, antibiotics in soap, and hormones from hormone therapy or birth control pills. He said that wastewater treatment centers are not required to remove those things, which can end up in our waterways. But these concerns are not typically associated with data centers.
Those wastewater treatment plants also fall into the same category as other industries because they must hold NPDES permits—and this also means they can be a part of that percent of industries in violation of EPA standards.
However you follow the water, the path seems to lead to unanswered questions, made all the more uncertain by a lack of comprehensive data on data centers and their relationship with water. Boritt said that the Indiana Wildlife Federation is not anti-data center, but that it has its worries.
“I do think we need to hold data centers to account for what they are doing to our environment and hold them to a standard which every other entity should be held to,” he said.
