Meta contaminates drinking water in Cheyenne by purging cooling system

What happened?

The Cheyenne Board of Public Utilities (BOPU) stopped accepting industrial wastewater from data center fill and purge operations after a Meta contractor, Goat Systems LLC, discharged water contaminated with the bacterium Cupriavidus gilardii into the sanitary sewer. The metal-resistant bacterium interfered with two water reclamation plants and forced the reuse system offline for months for cleaning. According to a report by Cowboy State Daily cited by Tom's Hardware, the BOPU revoked Goat Systems' discharge permits on March 24, and a broader suspension now covers all data centers connected to city services. Frank Strong, BOPU's engineering and water resources manager, told the Wyoming Tribune Eagle that the fill water was purchased from the BOPU itself and that the origin of the bacterium remains unknown, though lab staff detected it in February during routine fecal bacteria sampling. 'This is not something we normally test for,' Strong said.

Purging is a startup step where cooling circuit pipes are filled with water, purged to remove debris, and then the used water is drained. Although closed-loop liquid cooling is touted as nearly water-free, this incident shows that single-use water during installation can cause significant contamination. The case is not isolated: in 2023, a data center in the Netherlands accidentally discharged water with glycol into the sewer, damaging the local treatment plant. The bacterium Cupriavidus gilardii is particularly problematic because it is metal-resistant and can form biofilms in pipes, making it difficult to remove.

Why is this important?

Meta, Microsoft, and Nvidia promote liquid cooling as a sustainable alternative that drastically reduces water consumption compared to traditional evaporative cooling. Microsoft describes cooling systems that are filled once during construction and then recirculate the same water, while Nvidia's Rubin platform uses a coolant that, they claim, reduces water consumption to nearly zero. However, the Cheyenne case reveals that purge discharges can contain unregulated bacteria, glycol, and other chemicals that municipal plants are not designed to treat. The bacterium Cupriavidus gilardii is not a regulated contaminant, but its presence forced the shutdown of the reuse system that irrigates parks and golf courses, creating a potential risk of aerosolization during irrigation. According to Tom's Hardware, most new AI data centers in the U.S. are built on drought-affected land, making water management even more critical. The incident occurs amid a massive expansion of AI data centers, many located in water-stressed areas. The promise of 'zero water' from liquid cooling clashes with the reality that the initial fill process generates waste that must be properly managed. A 2024 study by the University of California estimated that a 100 MW data center can generate up to 500,000 liters of purge water during startup, a volume rarely accounted for in environmental impact assessments.

Consequences and lessons

The discharge suspension affects all data centers connected to the city, not just Meta. The BOPU revoked Goat Systems' discharge permits on March 24 and extended the suspension to any fill and purge operations. Meta says it supports its general contractor, Fortis, which has stopped discharging and now hauls waste off-site. Independent tests found no trace of the bacterium, though the BOPU confirmed its presence. City councilman Pete Laybourn called the revelation a 'very unpleasant surprise.' The case underscores the need for tech companies to implement stricter wastewater treatment protocols during the construction phase, and for municipalities to update their regulations to include emerging contaminants like metal-resistant bacteria. Comparatively, in 2022, a Google data center in Belgium had to temporarily shut down due to similar purge water issues, leading the company to develop an on-site treatment system. The lesson for the industry is that liquid cooling is not 'waste-free' and that purge discharges must be treated as hazardous industrial waste, not domestic wastewater. Additionally, the lack of regulation on bacteria like Cupriavidus gilardii creates a legal gap that could lead to more incidents as the technology expands.

What should readers know?

• Closed-loop liquid cooling is not waste-free: the initial purge water must be managed as industrial waste, not domestic wastewater. A single data center is estimated to generate between 200,000 and 500,000 liters of purge water per startup phase.
• Unregulated bacteria, such as Cupriavidus gilardii, can proliferate in pipe systems and affect municipal water infrastructure, as they are metal-resistant and difficult to remove with conventional treatments.
• The Cheyenne incident is not isolated; as more data centers adopt liquid cooling, purge discharges will increase. According to an Uptime Institute report, liquid cooling is expected to account for 30% of new data centers by 2027, up from 10% today.
• Companies must coordinate with local authorities on wastewater management plans before starting operations, and municipalities should update their regulations to include broader microbiological testing. The BOPU has already announced it will review its monitoring protocols to include metal-resistant bacteria in the future.

'This is not something we normally test for,' said Frank Strong, BOPU's engineering manager, about the detected bacterium. The lesson is that industrial discharges require broader monitoring than current regulations demand. Meanwhile, Meta has stated it is working with Fortis to ensure all waste is managed in accordance with local regulations, and they are evaluating on-site treatment technologies to prevent future incidents.