Which water-supply and discharge records qualify a data center site?

Which water-supply records qualify the site?

Qualify the proposed phase with five connected records: a supply commitment register, seasonal water balance, quality/treatment matrix, discharge approval register and curtailment sensitivity. Anvilfield's diligence framework keeps the issuer, document date, applicable phase, units, conditions and superseded version with each record. [S2] [S3] [S13]

A water right answers who may abstract water under its terms. A utility commitment answers what service the utility has allocated and under which conditions. An accepted connection records completion of specified works. Read the operative terms rather than assigning legal force from a document's title; a conditional will-serve letter supports only the quantity and conditions it actually states.

Place this evidence behind the water screen in the data center site selection criteria. Retain required environmental water assessments beside service instruments: an assessment records evaluated demand and resources; the service terms establish allocation. Berkeley CLEE's February 2026 report explains California's regulatory and information gaps; its policy recommendations are distinct from enacted requirements. [S10] [S13]

What does each document actually establish?

What belongs in the commitment register?

Use one row per source and phase. Capture supply type, issuing party, executed document ID, reserved quantity and time basis, connection point, earliest delivery, upgrade funding, expiration and restriction language. Keep priority class, drought reductions, reservation fees, milestone conditions, release terms and transfer provisions beside the quantities they change.

For an acquisition, obtain the seller's agreements, meter records, discharge permissions and outstanding upgrade obligations. Request the issuer's written transfer or reissuance determination for the acquiring entity and proposed phase. Resolve material prerequisites before treating the quantity as available; no universal letter-validity period replaces the actual expiration term.

A well log identifies a drilled source. Qualify direct abstraction with the right or permit, pumping-test duration, drawdown and recovery, seasonal yield and matching treatment infrastructure.

Is a utility commitment the same as available delivery capacity?

The allocation and the delivery study must support the same demand at the same connection and date. Water passes through a resource, permitted abstraction, treatment, storage, distribution and the service connection.

Loudoun Water's Pre-Design guidance, checked November 5, 2026, states that its existing-utility maps show pipe locations and sizes but do not provide pipe capacity or flows. [S2]

Request written confirmation of maximum-day volume, maximum instantaneous flow, service-boundary pressure under stated system conditions and phase-by-phase delivery dates.

Separate present service from capacity conditional on a pump station, main extension or treatment upgrade. Assign funding, construction responsibility and completion dates to each condition. The selected cooling-system type sets the process request; the fire-protection hydraulic case has its own design basis and any concurrency requirement imposed by the serving authority.

Apply the same delivery check to wastewater: obtain acceptance for the receiving treatment works and capacity through the lateral, sewer and any lift station at the proposed batch rate. A purchased average-day sewer allowance does not establish that a short commissioning discharge will fit the collection system.

Which water quantities and boundaries must match?

Record annual volume, average day, maximum day and maximum instantaneous flow separately. Annual water use and WUE relates water volume to IT energy; connection design also needs flow and pressure. Keep water withdrawn at the meter, evaporative consumption and liquid returned to sewer as separate quantities.

Trace makeup water through one site boundary: source meter to domestic branch and treatment feed; treatment feed to tower product and reject; tower makeup to evaporation, drift and blowdown; sewer to accepted domestic wastewater, reject, blowdown and separately scheduled batches. Keep electricity-generation water outside this parcel connection balance.

A closed IT loop still needs an outdoor heat-rejection path. Direct-to-chip liquid cooling connected to evaporative rejection retains tower demand. Dry rejection removes routine evaporative makeup only for the duty and weather it serves; list domestic demand, initial fills, cleaning, installed humidification or adiabatic backup, and fire service separately.

How do you avoid counting reuse and treatment twice?

Credit recovered condensate or onsite reuse only in months and rates supported by production records or an engineering calculation, with a named receiving use and acceptable chemistry. A treatment plant's product output is smaller than its feed whenever it rejects water.

Divide product demand by recovery to obtain source feed, then subtract product to obtain reject. The equations are: feed = product / recovery; reject = feed minus product; tower makeup = evaporation + blowdown + drift, adding leaks and overflow when present. DOE FEMP supplies the tower balance. [S1]

How do you build a seasonal water balance?

Build twelve monthly rows for every phase and separate maximum-day and instantaneous-flow calculations. Retain the weather-file location, period and version; coincident dry- and wet-bulb conditions; IT-load ramp; available equipment; and wet/dry mode hours. Compare normal-year, hot/dry-year and restricted-supply cases on the same boundary.

Selected-equipment calculations at local coincident load and weather establish the design demand. Preliminary equivalent full-load hours express a useful calculation basis; nominal tons alone do not establish annual consumption. Adiabatic and evaporative cooling and free cooling and economizers change the hours in each mode.

DOE FEMP's undated estimating table, checked November 5, 2026, assigns 21,920 gallons to a 400-ton chiller's tower at three cycles over 24 full-load hours; its six-hour calculation gives 5,480 gallons. [S4]

What does a completed monthly balance look like?

The Anvilfield estimates below use that DOE input with six equivalent full-load hours per day in December through February, twelve in spring and fall, and twenty-four in June through August. Domestic demand is 500 gpd and the assumed delivered allowance is 25,000 gpd. Separate treatment reject and onsite reuse are zero; retain both fields in the calculation sheet.

Multiply DOE's full-load daily value by hours divided by 24 and actual 2026 month length, then add domestic use for that month.

How do you test peak and commissioning demand?

Anvilfield estimates convert the summer total of 22,420 gpd to 15.57 gpm averaged across twenty-four hours. Obtain maximum inlet and refill rates from valve flow, controls and hydraulic design; the daily conversion does not size them.

A 20,000-gallon initial fill over eight hours adds 41.67 gpm. On the modeled summer operating day, that fill raises withdrawal to 42,420 gallons, exceeding the daily allowance by 17,420 gallons. Schedule it separately or secure a documented temporary allowance and sufficient instantaneous delivery. Check concurrent cooling, domestic demand, meter losses and approved disposal timing before placing the fill on the construction schedule.

Which quality and treatment records determine usable supply?

Source chemistry determines the usable operating range. Obtain dated laboratory records for conductivity, hardness, alkalinity, chloride, silica, sulfate and suspended solids, identified by source, sample point, method and units. Cover normal, seasonal and backup-source conditions; target new samples at uncovered source changes.

Compare makeup quality with predicted circulating chemistry at the proposed cycles of concentration and actual equipment materials. Potable classification alone does not establish compatibility. Keep tower chemistry separate from closed liquid-loop water treatment and chemistry, and include biological control, corrosion and scale protection in the treatment scope.

Where do manufacturer limits disagree?

BAC's Product & Application Handbook Volume VI, revision 20230630, and Marley's NC Class manual 00-1301F, copyright 2008, prescribe different normal pH ranges and startup conditions. Use the supplied model manual and actual materials for the project. BAC's circulating-water guidance is based on 95°F water, and mixed materials require their own review. [S5] [S6]

Normalize chloride units before comparison. BAC reports chloride as Cl; the cited Marley manual reports it as NaCl. Anvilfield estimates convert 500 mg/L as NaCl to about 303 mg/L as chloride using molecular masses, so comparing the printed numbers alone exaggerates their difference.

Which result limits the proposed cycles?

The following Anvilfield estimate inputs expose a chloride-only screening error. Multiplying source concentrations by four predicts acceptable chloride but excessive sulfate and silica, with conductivity at BAC's guideline.

This initial no-removal screen treats dilute-water ppm and mg/L as approximately equivalent. Conductivity multiplication is approximate and chemical additions change it. At three cycles, estimated chloride is 150 mg/L, sulfate 240 mg/L and silica 120 mg/L; sulfate retains the smallest fractional margin. Validate scaling, corrosion and biological control against the treatment design and operating temperature.

Divide a conservative-ion circulating ceiling by the source concentration to screen cycles. Do not multiply pH by cycles or use simple concentration arithmetic to accept reactive hardness or silica chemistry. Suspended-solids filtration does not remove dissolved chloride; softening addresses hardness, while membranes add a reject stream. [S1] [S11]

Include galvanized startup/passivation demand, chemistry and duration in construction scope. A proposed six-cycle plant remains conditional until product-water chemistry and the treatment guarantee support that concentration.

BAC's 20230630 guidance requires biological control during tower operation; corrosion and scale treatment alone does not control biological contamination. Retain the startup and ongoing biological-control scope, including storage-water management and authorized disposal of treated water. [S5]

Which discharge approvals must be in the register?

Identify the actual receiving system for every stream before selecting an approval route. EPA's NPDES Permit Basics distinguishes point-source pollutant discharges to waters of the United States, requiring NPDES authorization, from sanitary-sewer discharges governed by receiving-municipality requirements. A storm drain needs its own route and authorization determination. [S7]

Register tower blowdown, membrane reject, softener regeneration, basin drains, cleaning water, domestic wastewater and commissioning flushes. Obtain the receiving authority's classification for the actual additives and chemistry rather than treating all cooling discharge as noncontact cooling water.

Which federal and local thresholds matter?

EPA's explanation of 40 CFR 403.3(v), checked November 5, 2026, identifies average process wastewater of at least 25,000 gpd as a significant industrial user (SIU) trigger, excluding sanitary, noncontact cooling and boiler blowdown from that test. Other routes include categorical status, contribution of at least 5% of a publicly owned treatment works' (POTW's) average dry-weather hydraulic or organic capacity, and discretionary designation. Retain the control authority's classification and any applicable nonsignificant designation. [S8]

EPA's summary of 40 CFR 403.5 prohibits discharge below pH 5.0 unless the works is designed for it. It also prohibits heat that inhibits biological treatment and causes interference, and heat raising the POTW treatment plant above 40°C unless the approval authority approves an alternative at the POTW's request. These limits apply alongside local discharge conditions, including at smaller flows. [S9]

Loudoun's Broad Run local limits, approved by Virginia DEQ November 8, 2024, state pH 5.0 to 10.0, 40°C at the POTW and 60°C from an SIU. The program separately identifies TSS above 245 mg/L as abnormal strength requiring written approval. Apply those values to that receiving works. [S14]

EPA's construction-stormwater guidance covers disturbance of at least one acre and smaller sites within a common plan of development or sale reaching one acre, subject to applicable permitting rules. That coverage does not authorize routine blowdown or chemical flushes. [S12]

What monitoring and transfer records belong with approval?

Transcribe instantaneous, daily-maximum, monthly-average, batch and reporting conditions into separate fields. Record sample point, grab/composite method, laboratory method, flow basis, chain of custody and responsible organization. EPA's September 2012 Industrial User Permitting Guidance Manual explains the permit-specific structure; a generic monthly sampling allowance cannot replace it. [S15]

For an existing authorization, record operator, activity, outfall, expiry, renewal status and transfer conditions. Ask whether the new phase or chemistry requires modification. A seller's permit number or submitted application does not establish the acquiring operator's authorization. Keep sewer-credit metering separate: a blowdown meter supports billed volume while route and chemistry acceptance establish the discharge permission.

Does reclaimed water include enough backup capacity?

Record reclaimed quantity, pressure, chemistry, restrictions and downtime provisions separately from potable backup. Loudoun's current reclaimed program identifies supply availability and hydraulic constraints that can limit or exclude proposed connections. [S16]

Loudoun Water's October 9, 2026 Rates, Rules and Regulations sets potable backup capacity for reclaimed-water customers project by project, with a minimum of 10% of the reclaimed allocation. Schedule E also gives the utility allocation discretion and allows adjustments when reclaimed supply changes. [S13]

Complete-interruption coverage requires confirmed delivery, usable storage or supported demand reduction.

Loudoun's October 2026 Rule 20(d) requires an approved air gap where potable service supplies plumbing or process piping that also incorporates a secondary source, including reclaimed water. Retain the approved separation and switching design, valve capacity and refill rate. [S13] Recalculate treatment and blowdown for the backup source or blend; higher limiting dissolved solids can force lower cycles. Schedule startup and temporary fills separately from the reserve credited to operating backup.

How much curtailment can the design absorb?

Anvilfield estimates that the small phase needs 7,260 usable gallons for a 72-hour reduction to 20,000 gpd, or 67,260 usable gallons for a complete 72-hour supply loss, at constant summer demand of 22,420 gpd. The assumed 20% reduction is a design sensitivity, not a utility drought rule.

Subtract confirmed supply from required demand and multiply the positive shortfall by event duration to size usable storage. Divide an existing tank's usable water by the shortfall to calculate endurance. Exclude dead storage, minimum pump submergence, protected fire volume and unavailable compartments.

For the ideal chemistry rows, assume negligible drift and leaks, hold evaporation fixed and divide it by cycles minus one to obtain blowdown, then add evaporation for makeup: B = E / (C - 1); M = E + B. Storage is shortfall gpd × duration hours / 24.

DOE BMP 10 describes three-to-six-cycle savings as 20% makeup and 50% blowdown; the ideal fixed-evaporation balance used here gives 20% and 60%, respectively. [S1]

Record shared treatment, mains, power and drought restrictions between primary and backup sources. Two connections can share the same failure. For dry or hybrid alternatives, retain manufacturer capacity at required ambient and fluid temperatures with the available components, and include the electrical consequence in PUE and energy-efficiency calculations. Pump power, refill limits and discharge capacity remain separate checks.

Storage covers a finite interruption. For persistent curtailment, qualify a smaller wet-cooling load or another confirmed source; refilling storage requires supply above ongoing demand. Refill time equals depleted usable gallons divided by that surplus in gallons per day. Confirm the tank can recover before the next design event.

What costs and approval intervals belong in feasibility?

Loudoun's January 1, 2026 schedule charges maximum-day water capacity at $15.62 per gpd and average-day sewer capacity at $41.31 per gpd. Those denominators differ. Separate capacity purchase from metered use, then price main extensions, easements, treatment, storage, temporary service and construction with actual quantities. [S17]

The October 9, 2026 rules base commercial Tier 1 on reserved capacity, with excess at Tier 2. For the Tier 1 calculation below, 2026 rates are $4.42 per 1,000 gallons potable, $2.07 reclaimed and $6.59 sewer. Apply the governing tier rules to the phase's billing pattern. [S13] [S17]

How long do approvals take?

EPA says individual NPDES coverage can take six months or longer. Its Permit Basics gives an application interval of at least 180 days before discharge; 40 CFR 122.21(c)(1), July 1, 2025 edition, allows a later date granted by the Director and distinguishes general-permit submission dates. The filing interval is not an approval promise. [S7] [S19]

Loudoun lists ten working days for specified submittal reviews and five to ten business days for final signed construction-permit issuance after required documents are verified and approved. These are individual stages. Schedule upgrade design, easements, permit reviews, utility construction and service activation separately, with a responsible party and predecessor for each. [S3]

Worked example: what do the utility records change?

Loudoun's published January 1, 2024 connection comparison uses a 100,000-square-foot data center, 100,000 gpd maximum cooling water, 20,000 gpd average sewer, 50,000 gpd average cooling-water use and 10,000 gpd potable backup. The Anvilfield estimates below retain those quantities and apply verified 2026 prices. [S18] [S17]

The current process-meter estimating guideline instead gives 0.125 gpd per square foot sewer, yielding 12,500 gpd. It assumes 25% blowdown to sanitary sewer and excludes the domestic meter. Keep this estimating basis separate from the older comparison and secure the approved demand; the difference changes sewer capacity cost by $309,825. [S17]

For annual variable charges, multiply average daily use by 365, divide by 1,000 and apply the 2026 rates above. Anvilfield estimates that 18,250,000 gallons of cooling water costs $80,665 at potable Tier 1 or $37,778 reclaimed; 7,300,000 gallons of sewer costs $48,107. Combined annual charges are $128,772 and $85,885, respectively, with a $42,888 water saving calculated before rounding. Domestic service, fixed charges, extensions, treatment and storage remain separate budget lines. [S18] [S17]

Anvilfield estimates that 100,000 gpd of cooling demand with 10,000 gpd of confirmed potable backup needs 270,000 usable gallons to bridge a 72-hour loss of reclaimed supply at constant demand. Price greater firm backup, storage, a smaller phase or a supported alternate rejection mode against that shortage.

Can treatment make the same site fail both allowances?

The combined engineering balance below holds evaporation at 60,000 gpd, with negligible drift/leaks, 500 gpd domestic supply and sewer, a 100,500 gpd source ceiling and a 40,500 gpd total sewer allowance. Treatment delivers all tower makeup at 75% recovery, with all reject routed to the accepted sewer. These are Anvilfield estimate inputs, separate from the tariff example.

Anvilfield estimates that adding 75%-recovery treatment to a tower needing 90,000 gpd of makeup raises source demand and sewer flow by 30,000 gpd each, so water-quality treatment must be included in both capacity requests.

Divide product makeup by 0.75 for treatment feed and subtract product for reject. Source withdrawal is feed plus domestic use; sewer is blowdown plus reject plus domestic wastewater. Every row closes: withdrawal equals 60,000 gpd evaporation plus sewer flow. Retain the six-cycle alternative as conditional until product chemistry, sewer acceptance and delivery evidence support it; a recovery guarantee establishes a volume ratio, while product analyses establish chemistry.

Water-feasibility field checklist

Give each item an evidence location, responsible party, date and action. Under Anvilfield's recommended practice, documented means the phase fits the applicable quantity, hydraulic, quality and discharge conditions. Conditional identifies a named prerequisite; unresolved means the corresponding quantity remains unsupported.

Tie outstanding conditions to the acquisition and engineering schedule. When a quantity fails, change the phase, rejection plant, treatment, storage or source arrangement and rerun the same balance.

• Match parcel, service boundary, owner/entity and phase across every record; correct discrepancies.
• Record executed quantity, time basis, commencement, expiry and conditions; resolve missing allocations.
• Retain direct-source rights, permits and production evidence; exclude unsupported yield.
• Confirm water delivery and pressure and sewer batch capacity; resolve upgrades and losses.
• Retain monthly, maximum-day and instantaneous demand calculations; rerun after plant or load changes.
• Separate domestic demand, treatment feed/reject, temporary fill and expansion; close the balance.
• Identify dated source-quality records covering planned sources; tie cycles to equipment manuals.
• Assign startup/passivation chemistry, duration and disposal to construction scope.
• Name every receiving works or outfall and authorization; secure temporary flush permissions separately.
• Record discharge sample point, averaging basis, method and monitoring/reporting frequency; budget the program.
• Separate reclaimed allocation from potable backup; calculate interruption coverage.
• Record usable storage after reserves and dead volume; verify pumping, refill capacity and recovery time.
• Apply current capacity tariffs, use tiers and extension responsibilities; resolve competing sewer bases.
• Assign easements, upgrades, permits and activation to dated phase milestones.
• Resolve transfer, renewal, expansion and chemistry-change conditions with each issuer.
• Retain signed instruments, source PDFs, calculations, correspondence and superseded versions; repeat review after material changes.

How should the team scope water diligence and site screening?

Commission named deliverables: utility confirmation and connection design; source sampling and treatment design; the water balance; wastewater routing and permit applications; storage or alternate-mode design; and the commercial estimate and schedule. Price temporary supply and disposal within the construction and buildout phases, including commissioning fills and flushes.

Teams building a regional cooling-water diligence program use [PorchRocket Asset Search](/asset-search?for=cooling-towers) to locate visible cooling towers and get a reviewed list with the owner of record for each find. Request the site's utility agreements, process-water balance and discharge records from that owner as the starting document set.

For an occupied site, reconcile water and blowdown meter totals with billing records, equipment runtime and source changes. Explain gaps between recorded use and the proposed phase: low occupancy, dry-mode operation or incomplete buildout can conceal the future peak. Preserve raw readings and meter boundaries with the demand model.

Sources, method and citation

Sources checked and review date: November 5, 2026. DOE's web guidance is undated; named manuals, tariffs and regulations retain their editions below. Anvilfield's registers and checklist are diligence practices; Anvilfield estimates use the stated source inputs and engineering assumptions.

1. S1: DOE FEMP, Best Management Practice #10: Cooling Tower Management; undated guidance.
2. S2: Loudoun Water, Pre-Design; online procedure.
3. S3: Loudoun Water, Permitting Your Approved Project; online procedure.
4. S4: DOE FEMP, Estimating Methods for Determining End-Use Water Consumption; undated guidance.
5. S5: Baltimore Aircoil, Product & Application Handbook Volume VI, Water Quality Guidelines, file revision 20230630, pp. J184 to J186.
6. S6: SPX Cooling Technologies / Marley, NC Class Cooling Tower User Manual 00-1301F, copyright 2008, pp. 19 to 20.
7. S7: EPA, NPDES Permit Basics; online guidance.
8. S8: EPA, Pretreatment Roles and Responsibilities: Industrial Users; current online explanation of 40 CFR 403.3(v), checked 2026-11-05.
9. S9: EPA, Pretreatment Standards and Requirements: General and Specific Prohibitions; current online explanation of 40 CFR 403.5, checked 2026-11-05.
10. S10: UC Berkeley CLEE, Regulating Data Center Water Use in California, February 2026.
11. S11: EPA WaterSense, WaterSense at Work, original October 2012 compilation, cooling-tower section 6.3.
12. S12: EPA, Stormwater Discharges from Construction Activities; online guidance.
13. S13: Loudoun Water, Rates, Rules and Regulations, October 9, 2026 revision; rates effective January 1, 2026.
14. S14: Loudoun Water, Commercial and Industrial Wastewater Program; Broad Run local limits approved by DEQ November 8, 2024; checked 2026-11-05.
15. S15: EPA, Industrial User Permitting Guidance Manual, September 2012.
16. S16: Loudoun Water, Reclaimed Water Program; online program.
17. S17: Loudoun Water, Rates, Fees, Charges and Penalties; effective January 1, 2026.
18. S18: Loudoun Water, Reclaimed Connection Charge Comparison; expressly effective January 1, 2024.
19. S19: U.S. Government Publishing Office, 40 CFR 122.21(c)(1), July 1, 2025 annual edition, printed p. 189; checked alongside current EPA Permit Basics on 2026-11-05.

Update log, 2026-11-05: Rechecked all listed sources and calculation tables; clarified heat-discharge restrictions, sewer hydraulics, biological control, reclaimed-water separation and storage recovery; shortened repeated calculations.

How to cite this page: Anvilfield, Which water-supply and discharge records qualify a data center site?, 2026, https://anvilfield.com/field-guides/datacenter/data-center-water-feasibility-evidence/

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