What the Memphis reuse precedent actually demonstrates
A Memphis data center generally needs two coordinated treatment systems: polishing for reclaimed municipal wastewater used as cooling-tower makeup, and separate treatment or recovery for concentrated cooling-tower blowdown. The Memphis precedent supports this approach: the city plant treats about 40 million gallons per day, while the Colossus cooling loop requires 3 million gallons per day; additional filtration was needed to remove suspended solids. Final equipment selection depends on source-water chemistry, cooling cycles, blowdown-discharge route, permit limits, corrosion control and treatment objectives—not simply on daily water demand.
The reported figures describe one project arrangement, not a universal Memphis design standard. This Memphis data-center wastewater treatment framework should therefore be treated as a precedent for evaluating source availability and reuse logistics, then replaced with site-specific data.
Governing reported on March 16, 2026, that the city wastewater plant cleans about 40 million gallons per day, compared with the 3 million gallons per day needed by Colossus’s open cooling loop. The same report explains that the closed loop circulates continuously and does not need replacement. Heat transfers from that closed loop to an open cooling loop, where approximately 85% evaporates. Consequently, 3 million gallons per day is a source-water demand for this facility, not a measurement of all wastewater generated or blowdown discharged.
The additional treatment described at Colossus was essentially filtration to remove suspended solids before reuse. That finding supports a polishing step, but it does not establish the required filter type, treated-water targets or chemical controls for another site.
For regional context, USGS Circular 1405 reported 15.9 billion gallons per day of self-supplied industrial withdrawals in 2010; 82% came from surface water, and nearly all of that surface-water component was freshwater. This is historical national context, not a Memphis supply calculation or current withdrawal estimate.
Separate makeup-water treatment from cooling blowdown treatment
Makeup polishing and blowdown recovery require different objectives because they occur at different points in the cooling system and contain different contaminant profiles.
Reclaimed wastewater here means municipal effluent proposed for reuse as non-potable cooling makeup. Its suitability depends on a negotiated supply agreement, source-water characterization, additional treatment and the cooling designer’s water-quality requirements. It does not mean the data center assumes the effluent is already fit for its equipment.
Cooling blowdown is the portion removed from the cooling system to control accumulated solids, treatment chemicals and biological growth. Because the open loop loses water through evaporation, nonvolatile constituents become more concentrated than they are in the incoming makeup water. The data-center cooling blowdown treatment methodology applies the same stream-separation logic outside Memphis.
Drinking-water standards are not the automatic design basis for industrial cooling. The narrower basis is the chemistry needed to protect heat-transfer equipment, tower materials, fill and treatment chemicals, together with the requirements imposed by the supply agreement and authority having jurisdiction.
| Stream | Primary decision | Required engineering basis | Do not assume |
|---|---|---|---|
| Reclaimed municipal wastewater | Whether it can be polished for cooling makeup | Supply agreement, complete source analysis, cooling chemistry and equipment-protection targets | That city treatment alone proves suitability |
| Cooling-tower blowdown | Whether to recover, segregate, further treat or discharge it | Residual solids, concentration chemistry, permit route and reuse objective | That blowdown has the same quality as incoming makeup |
| Closed-loop water | Preserve heat-transfer performance and corrosion control | Closed-loop chemistry, metallurgy and heat-transfer specifications | That it is an additional consumable makeup stream |
Build the treatment train from source water to final discharge
A defensible treatment train begins with measured inputs and separates each subsequent decision by treatment objective.
- Characterize the inputs. Request average and peak reclaimed-water demand, a full analytical profile, cooling-loop chemistry, cycles of concentration, evaporation and blowdown calculations, and the selected discharge or reuse destination. If these inputs are unavailable, equipment capacity remains provisional.
- Protect the facility. Evaluate screening and pretreatment before fine filtration where the source may contain suspended solids, colloids, rags, plastics or fibrous debris. Potential chemistry concerns for the cooling assessment include hardness, alkalinity, silica, chloride, ammonia, organics and treatment residuals.
- Polish reclaimed wastewater. Use staged filtration suited to suspended-solids and colloidal removal. Place final disinfection or another microbial-control measure only where the cooling-system risk assessment establishes the need and the selected residual remains compatible with the loop.
- Manage cooling chemistry. Verify treated-water compatibility with tower metallurgy, heat-transfer surfaces, fill materials and chemical programs. This is an equipment-protection and process-control requirement, not a claim of potable-water quality.
- Treat blowdown separately. Evaluate recovery for reuse, segregation by contaminant, further biological or chemical treatment, and disposal. Compare the permitted route with recovery economics before selecting the final process.
- Monitor and verify. Tie monitoring to the approved water balance, treatment objectives and permit conditions. Relevant parameters can include conductivity, hardness, suspended solids, disinfectant or oxidant residual, microbiological indicators and scaling parameters.
Protect downstream equipment before committing to fine treatment. A rotary mechanical bar screen may be relevant where debris protection is required, while multi-media filtration for cooling makeup pretreatment can address suspended solids before downstream equipment. Screening is not a substitute for characterization; its necessity depends on the actual reclaimed-water stream.
| Process stage | Core question | Output needed for procurement |
|---|---|---|
| Characterization | What is in the source and cooling system? | Analysis, water balance, chemistry limits and permit route |
| Protection and pretreatment | What could damage pumps, valves, media or membranes? | Selected barrier, design flow and solids-handling method |
| Polishing | What removal is required before cooling? | Treated-water targets, flow basis and controls |
| Chemical and microbial control | Is dosing justified by source chemistry and risk? | Target, dose-control basis, storage and residual monitoring |
| Blowdown recovery or treatment | Where does the concentrated stream go? | Segregation, destination, permit basis and recovery targets |
Size the system from the water balance—not a gallons-per-day headline
The 3 million gallons per day open-loop makeup figure reported for Colossus is a case benchmark, not a design multiplier for every Memphis facility.
First separate daily source demand from treatment hydraulics. Average and peak daily makeup are different from instantaneous filtration and pumping rates. The treatment equipment must be assigned a design flow by the cooling designer, and the supplier must state whether that flow represents average demand, peak demand or an operating scenario with storage.
The site water balance must include makeup, evaporation, drift, blowdown and the planned loss or recovery fraction. The cooling designer must also establish cycles of concentration. At a given makeup flow, a different cycles-of-concentration value changes both blowdown discharge and the concentration of nonvolatile constituents. Without that calculation, neither blowdown treatment capacity nor contaminant loading is defensible.
Request the reclaimed-water supply duration, minimum and maximum flow, storage strategy and outage provisions. These inputs affect treatment reliability, equalization, pumping, controls and redundancy. Do not assume that continuous municipal supply means continuous delivery at the same rate.
| Sizing input | Why it changes equipment selection | Evidence required from the project team |
|---|---|---|
| Average and peak makeup demand | Separates daily inventory from hydraulic capacity | Cooling designer’s approved demand profile |
| Evaporation, drift and blowdown | Defines discharge and contaminant-load calculations | Complete water balance with assumptions |
| Cycles of concentration | Changes blowdown volume and nonvolatile constituent concentration | Approved cooling-chemistry calculation |
| Supply duration and outage terms | Determines storage and resilience requirements | Supply agreement and utility operating commitments |
| Recovery fraction | Changes residual discharge and treatment loads | Documented recovery objective and acceptance criteria |
Compare each treatment step at its expected peak demand, then evaluate redundancy and storage explicitly in the capital and operating comparison. Do not size every stage from the same unexplained daily average.
Choose equipment by treatment objective and operating risk
The correct equipment choice follows the contaminant, required removal, site constraints and operating risk—not the available package format.
Ultrafiltration systems for reclaimed wastewater polishing are suited to duties centered on low-turbidity, solids- and colloid-controlled separation with chemical-free membrane separation, automatic backwash and air scour. A multi-media filtration for cooling makeup pretreatment is suited to suspended-solids, turbidity and colloidal removal before downstream equipment, particularly where a conventional filter-vessel configuration is preferred.
Chemical dosing is not a default feature. Include an automatic chemical dosing system only when characterization establishes a controllable need such as coagulation, pH adjustment or specialty treatment. Define the target, compatibility with the reclaimed-water supply, storage, metering, interlocks and residual controls before accepting the scope.
| Option | Best-supported treatment objective | Key qualification |
|---|---|---|
| Screening or mechanical pretreatment | Remove rags, plastics or fibrous debris before downstream equipment | Selection depends on observed source-water debris |
| Multi-media filtration | Remove suspended solids, turbidity and colloidal matter | Define treated-water targets and backwash or media-handling requirements |
| Ultrafiltration | Control solids and colloids through membrane separation | Assess feed compatibility, recovery, backwash and air scour |
| Chemical dosing | Meet a demonstrated treatment target | Do not specify chemical need without source characterization |
| Packaged sewage treatment | Address a defined wastewater-treatment duty | Do not default to it for large reclaimed-water polishing; match flow, footprint, objective and route |
For another regional application of the engineering method, see the regional data-center wastewater treatment guide.
Convert the concept into a supplier-ready equipment scope
Comparable bids require bidders to solve the same documented problem and disclose the operating assumptions behind their proposals.
Issue the written source-water analysis, complete cooling water balance and selected discharge route as common attachments. Require each bidder to state design flow, peak-flow provision, treated-water targets, footprint, utility demand, controls, redundancy, membrane or media life, maintenance access and alarm provisions. Clarify treated-water guarantees, control philosophy, chemical storage, solids or spent-media handling, operator training, commissioning tests and warranty boundaries.
Require written confirmation that the proposed process was reviewed against the actual permit, water-reuse agreement and downstream cooling-equipment warranty requirements. If any of those documents remain unresolved, identify that limitation in the proposal rather than treating it as a compliance assumption.
Schedule is also part of the scope. Governing reported that construction of the Colossus Water Recycling Plant began in October 2025, with an original end-of-2026 completion target later described as hazy because of weather delays and other factors. That date is evidence of the need for a defined delivery schedule and schedule-risk allocation, not proof that the plant achieved operation in 2026.
| Bid package | Minimum requested content | Acceptance check |
|---|---|---|
| Design basis | Source analysis, water balance, peak-flow basis, permit route and recovery objective | All bidders use the same inputs and assumptions |
| Process and equipment | Treatment stages, duty basis, materials, controls, utilities and redundancy | Each component has a stated function and capacity |
| Operations | Maintenance access, media or membrane life, chemicals, waste handling and training | Lifecycle obligations are assigned |
| Compliance and handover | Permit review, commissioning tests, guarantees and warranty boundaries | No compliance claim relies on an unresolved document |
| Delivery | Milestones, schedule assumptions, delay provisions and acceptance criteria | Delivery obligations and responsibilities are explicit |
Frequently Asked Questions
Can reclaimed municipal wastewater be used for data-center cooling in Memphis?
Yes, if the utility, data-center operator and cooling designer establish an executable supply and treatment arrangement. The Colossus precedent shows that treated municipal wastewater can supply an open cooling loop, but it also shows why further suspended-solids filtration was needed. A different facility still needs its own source analysis, supply agreement, cooling-chemistry assessment and equipment-protection targets.
What treatment does cooling-tower blowdown need before discharge?
That depends on the blowdown chemistry, residual solids, treatment chemicals, biological-control status and selected permit route. A recovering site may need segregation and further treatment before reuse; a discharging site may require treatment to meet its permit conditions. The project team should request the approved water balance, residual-solids analysis, chemical program, discharge destination and applicable permit before selecting a process.
How much does a wastewater-reuse treatment system cost for a Memphis data center?
No defensible price can be stated from the available project evidence. A bidder needs the average and peak makeup demand, source-water analysis, treatment targets, storage and redundancy requirements, footprint, utilities, controls, waste handling, commissioning scope and delivery schedule. Request itemized capital and operating costs tied to those inputs, including membrane or media replacement, chemical use, energy and maintenance. Comparing a complete treatment scope is more useful than comparing a headline gallons-per-day price.
Should a data center choose ultrafiltration or multi-media filtration?
Choose ultrafiltration when the principal objective is solids- and colloid-controlled polishing through membrane separation, and choose multi-media filtration when the duty is suspended-solids and turbidity removal with a conventional filter-vessel approach. Final selection should also reflect feed compatibility, recovery, footprint, controls, maintenance, redundancy and treated-water targets. Neither option is justified without the source-water analysis.
How can a supplier compare bids for a Memphis cooling-water treatment project?
Issue one common basis and require explicit responses. Check that every bid identifies its design flow, peak-flow treatment, treated-water targets, pretreatment logic, redundancy, utility demand, controls, maintenance, waste handling, commissioning tests, warranty boundaries and permit assumptions. Require the bidder to identify any unresolved dependency in the permit, supply agreement or cooling-equipment warranty. Also verify that delivery milestones and delay responsibilities are explicit rather than assumed from the project schedule.
