Quick Answer
Data centers cut water and sewer costs fastest by attacking the sewer side of the bill, not just the water side. Sewer rates often exceed water rates — San Antonio Water System’s 2026 general-class schedule charges $4.368 per 1,000 gallons for sewer versus $1.958 for base water — and most utilities bill sewer on total metered intake, even though evaporative cooling sends most of that water into the atmosphere. Seven levers, ranked roughly by return for effort: review your rate schedule, claim sewer and evaporation credits through submetering, raise cooling tower cycles of concentration (moving from 3 to 6 cycles cuts makeup water 20%, per EPA WaterSense), meter and monitor to catch leaks, tune cooling operations, reuse on-site water such as air handler condensate, and connect to reclaimed water where a utility offers it.
The Data Center Water Cost Stack: What You Actually Pay For
A data center water bill has three main layers: a volumetric water charge, a volumetric sewer charge, and fixed service charges tied to meter size. Some utilities add capacity or demand components on top. Before you can cut costs, you need to know which layer dominates — and at many utilities, it is sewer.
San Antonio Water System’s 2026 general-class rates (inside city limits) illustrate the pattern: base water costs $1.958 per 1,000 gallons (rising to $3.427 in the highest usage tier), while sewer costs $4.368 per 1,000 gallons — more than double the base water rate. Monthly service availability charges scale with meter size, exceeding $1,000 per month for a 12-inch meter. Rate structures like this mean a facility can pay more to dispose of water it never discharges than it pays to buy the water in the first place.
That last point is the structural problem. Most utilities calculate the sewer charge from the incoming water meter, assuming everything you buy goes down the drain. But evaporative cooling — still the dominant heat-rejection method behind the numbers in our pillar guide to how much water data centers use — consumes most of its water. According to Lawrence Berkeley National Laboratory’s 2024 United States Data Center Energy Usage Report, U.S. data centers directly consumed about 66 billion liters (roughly 17 billion gallons) of water in 2023. Consumed water is, by definition, water that never returns to the sewer — for evaporative cooling, it leaves as vapor.
EPA’s WaterSense at Work guidance (2023) notes that cooling towers often represent the largest water use in commercial and institutional facilities, comprising 20 to 50 percent or more of total water use — and in a data center running evaporative cooling, the share is typically far higher. Every gallon that evaporates but still gets billed as sewage is a recoverable overpayment.
7 Levers to Cut Data Center Water and Sewer Costs
Here are the levers ranked by effort against return, with the tradeoffs stated plainly. Rankings assume a facility with evaporative cooling on a municipal water and sewer connection; your mileage shifts if you run air-cooled or already use reclaimed water.
| Lever | Effort | Typical return | Main tradeoff |
|---|---|---|---|
| 1. Rate schedule and bill review | Low | Low–moderate, one-time corrections plus ongoing rate-class savings | Savings capped by tariff options |
| 2. Sewer / evaporation credits | Low–moderate | High and recurring; often the largest single line item | Requires submetering, documentation, and utility approval |
| 3. Cycles of concentration optimization | Moderate | Up to 20% less makeup water (3 to 6 cycles) | Scale and corrosion risk; limited by makeup water chemistry |
| 4. Metering, monitoring, and leak detection | Low–moderate | Variable; enables every other lever | Upfront meter and telemetry cost |
| 5. Operational efficiency (WUE) | Moderate | Moderate; saves energy and water together | Tighter thermal margins require engineering review |
| 6. On-site water reuse | Moderate | Modest, site-dependent | Seasonal supply; retrofit plumbing |
| 7. Reclaimed water connection | High | High where available | Geography-limited; water quality management |
1. Review Your Rate Schedule and Bills
Start with the cheapest audit there is: read your tariff. Large water users are sometimes on the wrong rate class, paying for a larger meter than the connection requires, or missing an industrial or interruptible schedule the utility offers. Multi-meter campuses accumulate errors — irrigation deducts, fire-line charges, and estimated reads that never got trued up.
The return is usually modest but the effort is near zero, and the review builds the usage baseline you need for every lever below. Pull 24 months of bills and reconcile them against actual meter reads before doing anything else.
2. Claim Sewer and Evaporation Credits
This is the highest-return lever for most evaporative-cooled facilities because it attacks the most expensive gallon: the sewer-billed gallon that never reached the sewer. An evaporation credit (some utilities call it a sewer credit or sewer deduction) adjusts your sewer bill to reflect only the water you actually discharge — typically documented by submetering cooling tower makeup and blowdown, the concentrated water periodically drained from the tower.
The math is straightforward. Assume 100,000 gallons per day of cooling tower makeup at 4 cycles of concentration, with sewer billed on the full incoming meter at San Antonio’s 2026 rate of $4.368 per 1,000 gallons. At 4 cycles, blowdown is roughly 25,000 gallons per day, meaning about 75,000 gallons per day evaporates. That is 27.4 million gallons per year billed as sewage but never discharged — about $119,600 per year in sewer overpayments at that rate.
The tradeoffs: you need meters the utility trusts, documentation it accepts, and in many cases a formal application. Utilities that offer these credits grant them because their own rules say customers should pay for the wastewater service they actually use — but they rarely volunteer them. Availability and rules are jurisdiction-dependent: some utilities run formal programs, some handle requests case by case, and some offer no adjustment at all. Our guides to evaporation credits for data centers and submetering for sewer credits cover the qualification process step by step.
3. Optimize Cycles of Concentration
Cycles of concentration measures how many times water recirculates through a cooling tower before being drained as blowdown — approximately the ratio of makeup water to blowdown water. Higher cycles mean less water purchased and less water discharged. EPA’s WaterSense at Work guidance reports that many systems operate at 2 to 4 cycles while 6 or more may be possible, and that increasing cycles from 3 to 6 reduces makeup water by 20 percent and blowdown by 50 percent.
EPA’s 20 percent figure assumes a tower starting at 3 cycles. The example facility above already runs at 4 cycles, so its ceiling is smaller: holding evaporation constant at 75,000 gallons per day, moving from 4 to 6 cycles cuts makeup from 100,000 to 90,000 gallons per day — a 10 percent reduction, or about 3.65 million gallons per year. That is worth about $7,100 in water charges at San Antonio’s base rate, or roughly $23,100 combined if sewer is still billed on the incoming meter. The Federal Energy Management Program’s cooling tower guidance recommends installing a conductivity controller so blowdown happens automatically only when dissolved solids exceed the set point, rather than on a timer.
Be honest about the tradeoff: pushing cycles higher concentrates dissolved minerals, which raises scale and corrosion risk and demands tighter chemical treatment. The ceiling depends on your makeup water quality, so set targets with your water treatment vendor, not against a generic benchmark. For the underlying mechanics, see our explainers on cycles of concentration and cooling tower blowdown.
4. Meter, Monitor, and Find Leaks
You cannot manage a flow you do not measure — and most operators do not measure. Lawrence Berkeley National Laboratory’s Center of Expertise for Data Centers reports that less than a third of U.S. data center owners and operators measure and track water consumption. That gap hides leaks, overflow events, stuck float valves, and blowdown valves that never fully close, all of which bill at full water-plus-sewer rates around the clock.
Submeters on tower makeup and blowdown, with remote monitoring, catch these anomalies in days instead of billing cycles — and the same meters generate the documentation that sewer credits and WUE reporting require. One meter investment feeds three levers. Our practical guide to water submetering for data centers covers meter selection and placement.
5. Improve Operational Efficiency (WUE)
Water usage effectiveness (WUE) — total site water consumption divided by IT energy use, in liters per kilowatt-hour — falls when you reject less heat through evaporation. The Federal Energy Management Program’s data center cooling guidance points to low-cost operational moves: ASHRAE recommends IT inlet temperatures up to 80°F, so raising conservative setpoints cuts chiller load and tower evaporation, and hot-aisle/cold-aisle containment can reduce chiller energy consumption by about 20 percent. Water-side economizers bypass chillers during cool weather.
These are fundamentally energy projects with water savings attached, so they compete for capital with everything else on the engineering roadmap. The tradeoff is thinner thermal margin, which makes airflow modeling and staged rollout worth the extra diligence.
6. Reuse Water You Already Have On Site
The Federal Energy Management Program highlights air handler condensate as a cooling tower makeup source that needs little or no pretreatment: it is low in minerals and is produced in the greatest quantities exactly when cooling loads peak. Captured rainwater and foundation drainage can serve the same role at some sites.
Returns are real but modest — condensate volumes are a fraction of tower demand — and supply is seasonal. Treat reuse as a complement to the billing and chemistry levers above, not a substitute.
7. Connect to Reclaimed Water Where It Exists
Some utilities sell highly treated wastewater — reclaimed water — for industrial cooling, often at a discount to potable rates and outside potable drought restrictions. Loudoun Water in Northern Virginia’s Data Center Alley built its first reclaimed water pipelines in 2010 specifically to serve data centers; the system has grown to 20 miles of pipeline and delivered more than 750 million gallons in 2025, offsetting an equal volume of drinking water.
This is the highest-effort lever: it requires being near a purple-pipe network, negotiating a connection, and managing different water chemistry in your towers. Where available, it pairs well with evaporation credits, since reclaimed supply lowers the water side of the bill while credits fix the sewer side.
Where to Start: A 90-Day Sequence
In the first 30 days, pull 24 months of bills, confirm your rate class and meter charges, and calculate your implied evaporation from makeup and blowdown data. In days 30 to 90, install or certify submeters, file for sewer and evaporation credits with your utility, and have your treatment vendor evaluate a cycles-of-concentration target. Longer-horizon projects — containment, economizers, condensate capture, reclaimed water — can then be ranked with actual dollar figures instead of estimates.
Sequence matters because the billing levers fund the engineering levers. A six-figure recurring sewer credit approved this quarter pays for meters, controllers, and studies many times over.
Ready to Find Out What You Could Save?
Data centers with evaporative cooling often pay sewer charges on millions of gallons that never reach the sewer. RPM Water Equity Solutions works with nearly 200 utilities across 36 states to document evaporation and recover those overpayments.
Request your free assessment today and find out how much you could recover.
The Bottom Line
Water and sewer costs are one of the few data center operating expenses where a paperwork lever — billing corrections and evaporation credits — can outperform capital projects. Start with the bill, add the meters, then let verified data drive the chemistry and engineering decisions. As utilities tighten scrutiny of large water users, the operators with documented flows will be the ones paying only for what they actually use.
