Water management has become a focal point in the majority of conversations about data center development. As AI and cloud computing services drive demand for processing capacity, digital infrastructure’s impact on local water supplies is drawing scrutiny from municipalities, regulators and the public.

Residents have raised questions about rising utility bills and strains on municipal water systems. A recent Gallup poll found that half of Americans opposed to local data centers cite concerns about excessive use of water resources. More than 100 local moratoriums on data center construction have been passed, most frequently by county- and city-level jurisdictions.

In light of these pressures, increasing the efficiency of water use in data centers is critically important. Wastewater treatment solutions are emerging as a key supporter of data center operations, providing additional treatment for municipal wastewater sources or treating water circulated within closed loop cooling systems. Cooling functionality is essential to protect sensitive data center equipment, so water treatment technologies must meet high standards for removing contaminants and ensuring reliable system performance.

From pretreating reclaimed wastewater to managing blowdown from evaporative cooling towers, ultrafiltration (UF) membrane technology provides a low-energy and space-efficient filtration option that effectively removes total suspended solids (TSS), helps protect cooling equipment from fouling, scaling, and corrosion and supports water reuse at scale.

For a comprehensive review of how membrane filtration helps meet the needs of data centers, it is useful to examine the current environment around water usage and the challenges that water treatment systems face in these facilities.

Investments in water stewardship

Many major data center owners have adopted a zero-impact approach for new data center sites with commitments to protect water resources, such as the pursuit of alternative water sources and less water-intensive cooling systems. For example, Google uses treated wastewater from Douglas County’s water and sewer authority at its Georgia data center campus, and Amazon Web Services expanded its use of reclaimed wastewater to over 120 locations in the U.S. In Michigan, OpenAI and Oracle plan to use a closed-loop cooling system for the hyperscale Stargate data center project.

Policymakers are also exploring ways to encourage data centers to invest in water infrastructure. In May, U.S. Senators Ben Ray Luján (D-N.M.) and Katie Britt (R-Ala.) introduced a bill that would provide federal tax credits for water reuse projects. The Advancing Water Reuse Act targets projects that add on-site water recycling systems as well as municipal water recycling upgrades.

These initiatives highlight the need for advanced water treatment technologies that are capable of supporting alternative water sources and maximizing reuse opportunities for data centers.

Types of data center cooling systems

Cooling systems are the largest consumer of water in data center operations. They are designed to remove the large amounts of heat generated by servers, and as computing workloads increase rack density, the demands placed on cooling systems are increasing as well. While some facilities use air cooling systems, many data centers rely on water cooling systems due to water’s higher thermal conductivity.

The most common cooling approach for data centers is evaporative cooling, which uses low amounts of energy but is more water intensive. In evaporative systems, water absorbs heat from servers and enters cooling towers to release the heat into the atmosphere. As water evaporates, dissolved minerals and solids concentrate throughout multiple cooling cycles. The concentrated liquid, known as blowdown, is eventually purged.

In closed-loop water cooling systems, water circulates through sealed pipes without being exposed to air, meaning it is continuously reused with smaller top-off additions. According to data from the World Economic Forum, closed-loop systems can reduce water consumption by more than 50% compared to open evaporative methods. The tradeoff, however, is that closed-loop cooling systems require more complex piping systems that use higher amounts of energy to operate.

In areas with water scarcity, closed-loop systems minimize water withdrawals. For strained power grids, evaporative cooling may be specified because it uses less electricity. Data center owners must carefully balance local water availability, energy costs and infrastructure constraints to select the optimal cooling technology.

Regardless of the type of cooling system, water quality is an important factor that affects both operational efficiency and maintenance requirements.

Concentration and corrosion challenges

In evaporative cooling systems, blowdown can present multiple challenges for filtration systems depending on the facility’s water source. Scaling minerals, such as calcium and magnesium, as well as scale inhibitors, biocides and other chemical treatments can accumulate quickly.

TSS are also elevated in blowdown, which can be difficult for municipal wastewater treatment facilities to remove. This can result in increased fees for data center owners that discharge cooling effluent into municipal water systems.

States also have their own individual treatment requirements for discharges to surface waters such as rivers. Some locations require data centers to obtain National Pollutant Discharge Elimination System (NPDES) permits from state authorities that include discharge limits and reporting requirements. NPDES permits typically take 18 months or more to obtain, delaying tight data center construction timelines.

The focus on reclaimed wastewater for data center cooling also requires effective pretreatment solutions. Treated wastewater can vary widely in terms of quality and contamination, and can include not only organic waste but also surfactants that can be difficult to remove. The successful use of alternative water sources depends on treatment systems that can consistently remove solids, biological contaminants, soaps and oils before the water enters cooling infrastructure.

When minerals build up on heat exchange surfaces, they reduce cooling efficiency and shorten equipment lifespan. Microbiological growth can clog pipes and cause blockages, and corrosion can damage metal piping. If incoming water sources are not properly treated, these conditions can increase energy consumption and result in additional downtime caused by cleaning or repair.

Water treatment solutions

To address these treatment challenges, data centers are exploring several different approaches to water management. Some data center facilities are investing in on-site water treatment systems. These can serve as pretreatment for reclaimed wastewater that will be used in the cooling system. In closed-loop cooling systems, on-site water treatment can help maintain water quality and remove concentrated minerals so the water can continue to be reused within the data center.

Another avenue is partnering with municipal utilities to expand wastewater treatment infrastructure. In Quincy, Washington, Microsoft partnered with the city to build the Quincy Water Reuse Utility (QWRU). Microsoft was able to reduce its use of potable groundwater by an estimated 138 million gallons of water per year by transferring its blowdown water to the QWRU. Utilizing UF and reverse osmosis (RO) treatment processes, the treated water is then returned to the data center for cooling.

Benefits of advanced membrane technology

UF membranes are ideally suited to meet the needs of data center cooling systems. UF effectively removes suspended solids and emulsified contaminants that can damage cooling equipment without the added chemicals and reagents needed by traditional filtration techniques. Today’s spiral-wound UF membranes provide highly efficient separation with low energy consumption and a compact footprint.

In the past, conventional cast membranes made from polyacrylonitrile (PAN) or polyvinylidene fluoride (PVDF) were vulnerable to fouling. Their two-layer construction, with a large pore layer covered by a thin surface layer that defined porosity, made them difficult to clean. Single-layer, thermoplastic composite membranes address these limitations through a hybrid material architecture.

The membrane combines a hydrophobic polymer and a hydrophilic inorganic filler. The high surface area of the filler utilizes capillary forces to pull water through the membrane for a high flux rate, which can be two to four times higher than cast polymeric membranes. Super-hydrophilic anti-fouling coatings help prevent the accumulation of oils and other emulsified materials, and the single layer allows backwashing through flow reversal without delaminating the membrane.

With the ability to separate TSS to fewer than 10 ppm, UF membranes are ideal as a prefiltration step for RO systems. RO is highly selective, but its membranes are particularly susceptible to fouling. By incorporating composite UF membranes, operators can help reduce RO fouling rates and cleaning requirements. The combination of UF followed by RO is very common for treating reclaimed wastewater and blowdown streams.

Modular water systems

With the multiple layers of filtration achieved in spiral wound membranes, fewer modules are needed to process high volumes of water, enabling a smaller physical footprint for facility filtration systems. Compact filtration design options support the increasing use of modular units in data center construction.

For new data center construction, containerized water treatment systems can be installed at any point in the construction process, eliminating one of the potential bottlenecks for project completion. For existing facilities, modular systems can be added with minimal construction disruption. If water treatment needs increase, the systems can be scaled by adding modules as needed.

Summary

As owners and operators work to balance responsible water management with operational reliability, water filtration will become an enabling technology for the data centers of the future. UF membranes provide an efficient filtration solution that supports water reuse and wastewater recovery initiatives to better protect water resources, meeting the goals of data center companies to reduce water demand and addressing the concerns of community members in areas where data centers are constructed.