Water-Related Permits for Data Centers
The siting and operation of a data center, with or without water-based cooling systems, may require engaging with a set of administrative or permitting programs. These include activities governing:
While federal statutes such as the Clean Water Act (CWA) and Safe Drinking Water Act (SDWA) establish the overarching framework and authorities, most implementation occurs at the state, Tribal, and local level. Specific permitting implications will vary from project to project because of differences in the data centers themselves and the particular entities that will have jurisdiction over individual projects. Nonetheless, potential decision points are described below, outlining a broadly applicable structure.
Construction Phase
Site Location or Conditions
The geographic location of a data center can introduce regulatory complexity. If construction could impact wetlands or other jurisdictional waters, the project may require a CWA Section 404 permit from the U.S. Army Corps of Engineers, along with a corresponding CWA Section 401 water quality certification from the state or tribe. This combination represents a potential constraint on siting and can affect project timelines and feasibility.
Site Preparation
Typically, site preparation presents the first regulatory threshold associated with water-related permits. Projects disturbing one or more acre(s) of land are required to obtain coverage under a National Pollutant Discharge Elimination System (NPDES) permit. Coverage is most often provided by a Construction General Permit (CGP), provided by EPA or an NPDES authorized state. A CGP establishes pollution prevention and sediment and erosion control requirements for stormwater discharges to a water of the United States (or may also include state waters when a state is the permitting authority.
Operational Phase
Water Supply
Once construction considerations are addressed, the next major decision point concerns the source of water used for operations. For data centers, the primary operational uses of water are associated with cooling. The availability and subsequent choice of water supply fundamentally shapes the regulatory pathway that follows.
Municipal Drinking Water Supply
The majority of data centers depend on municipal drinking water supplies for their cooling water. In these cases, the facility itself typically does not require a new federal permit. Instead, the relationship is governed by a service agreement with the local utility, which must ensure that sufficient capacity and reliability exist to meet demand. In this scenario, SDWA requirements remain applicable at the utility level rather than the end user.
Alternative Supplies
In a small subset of scenarios, data centers may develop their own water supply, such as through groundwater wells or surface water withdrawals. Although data centers internationally use seawater for cooling, EPA has not found any such documented cases in the United States. Data centers relying on groundwater or surface water enter a different regulatory space, which is specific to the state in which they are located.
Groundwater withdrawals may be subject to state-issued permits that establish pumping limits, monitoring requirements, and aquifer protection measures. Surface water withdrawals may be similarly regulated at the state level, but may also introduce additional federal considerations.
Discharge and Wastewater Management
For water-cooled data centers, large volumes of water are used to cool processors and servers. Water may be cycled through the cooling system multiple times before it is eventually discharged as blowdown. The final destination and contents of discharges from cooling systems – which can contain added biocides and anticorrosion chemicals or are sometimes mixed with effluent from other non-cooling operations at the site (e.g., sinks and toilets) – impact which wastewater discharge regulations may apply.
Municipal Sewer
The most common destination for water discharged from a data center is a Publicly Owned Treatment Works (POTW), though privately owned treatment works or centralized waste treatment (CWT) facilities may also receive effluent from data centers. In the case of discharge to a POTW, the data center operates under a pretreatment program, typically administered by the local utility under state, Tribal, or EPA oversight. This program requires a data center to characterize its wastewater and ensure compliance with limits on parameters such as total dissolved solids (TDS), metals, and chemical additives.
Discharge to Surface Water
Where discharge occurs directly to a surface waterbody, such as to a stream, river, or lake, a NPDES permit is required, which establishes effluent limits, monitoring requirements, and reporting obligations. While other industrial sectors commonly discharge effluent in this manner, this pathway is less common for data centers, but may arise in locations without access to municipal wastewater infrastructure.
Alternative Disposal
Alternative disposal methods introduce additional permitting frameworks. Facilities that inject wastewater or treatment residuals into subsurface formations must obtain authorization under the Underground Injection Control (UIC) program, administered under the Safe Drinking Water Act. Similarly, land application or infiltration of wastewater may require state-issued permits governing nutrient loading, soil conditions, and groundwater protection. On-site storage or treatment systems, such as impoundments or lagoons, may need to comply with design, construction, operation and permit standards to protect groundwater and surface water quality.
Wastewater Treatment and Reuse
In cases where a data center sends its wastewater to a municipal sewer, the POTW is subsequently responsible for appropriate management and treatment of its own discharge; in most cases, this discharge is managed under the POTW’s existing NPDES permit. The data center’s responsibility is to ensure that its discharge to the POTW remains within the limits established by the pretreatment program and local sewer use ordinances.
However, after a POTW treats wastewater, usually mixed with municipal sources, some POTWs are authorized by states to reclaim that treated wastewater for a secondary beneficial use. In some cases, that includes use as cooling water for data centers.
Wastewater, when reused as a cooling water source, introduces a distinct and evolving regulatory layer. Although EPA has established guidelines on water reuse and recycling, no federal water reuse regulations exist. Many states have developed water reuse regulations or guidelines that define allowable uses, treatment standards, and monitoring requirements for reclaimed water. These frameworks differ considerably across the country. Some states have well-developed programs specific to industrial cooling, while others rely on more general or case-by-case approaches.
In addition to regulatory approvals, reuse systems depend on contractual agreements between wastewater utilities and end users. These agreements establish the terms under which reclaimed water is supplied, including volume, reliability, water quality specifications, and operational responsibilities. Although not permits in the formal sense, these agreements are often critical to project feasibility and function as a parallel administrative mechanism. In some cases, a utility will also provide a backup supply from drinking water sources, should the reclaimed water source falter.
There are some jurisdictions where the regulatory structure extends further to include permits for both the producer and the user of reclaimed water. Under this model, the utility holds authorization to generate reclaimed water, while the data center may require a separate approval governing its use within cooling systems.