Water: the real picture
Water is the issue residents raise most often, and it is the issue most worth understanding in detail. The water footprint of a data center is not fixed — it varies enormously with the cooling architecture the developer chooses. The same megawatts of computing power can be cooled with five million gallons of water per day, or with effectively zero, depending on which technology is selected at the design phase.
Where the water goes
Most data center water is used for cooling. The two largest uses are:
- Server cooling — Pulling heat away from the servers and their chips (CPUs and GPUs). Older designs do this with evaporative cooling towers (water evaporates into the air, taking heat with it). Newer designs circulate liquid in sealed loops, with much less evaporation.
- Power plant cooling — If the data center has its own on-site gas-fired power plant, that plant also needs cooling. This is a second, separate water load that can be larger than the server cooling itself.
Why the design choice matters so much
| Cooling design | Water use | Rough premium vs. baseline |
|---|---|---|
| Open evaporative cooling towers | Baseline — 3–5 million gallons per day | Lowest cost |
| Hybrid wet/dry cooling | 60–80% less than baseline | 10–20% premium |
| Closed loop with adiabatic assist | Around 90% less | 15–30% premium |
| Direct-to-chip liquid cooling | Very low, mostly sealed loop | Roughly comparable cost at high-density AI loads |
| Dry-cooled (no evaporation) | Essentially zero process water | 30–40% premium, small efficiency loss |
The capital cost difference between the worst and best water designs is meaningful but not prohibitive — typically 10% to 30% on the cooling portion of the project, with payback through reduced operating costs. At AI-class compute densities, modern liquid cooling is often cheaper, not more expensive, than older designs.
What a county CBA does
The CBA contains specific water provisions:
- Open evaporative cooling is prohibited as the primary cooling method for either the data center or the on-site gas plant.
- Environmental catch basins or process discharge basins, installed, properly lined, and monitored.
- Water sources must be used in priority order: rainwater first, recycled water second, treated municipal effluent third, brackish groundwater fourth, freshwater last.
- A volumetric cap is set on freshwater withdrawal.
- Monitoring wells around the site, paid for by the developer, with quarterly public reporting.
- A “drawdown trigger” — if water levels in the monitoring wells decline beyond agreed thresholds, additional construction phases must pause.
- Water-positive offsets: the developer funds projects (aquifer recharge, agricultural efficiency, conservation) that compensate for any freshwater used.
Bottom line — A hyperscale data center can still be a meaningful water user even under the strictest design. But the difference between a default design and a community-protected design is dramatic — measured in millions of gallons per day. The CBA’s job is to make sure the county gets the smaller number.
Next in this series
Power, the grid, and your electric bill →
County Community Education Series · Prepared by Scope Technology and Manufacturing as advisor to Texas residents of unincorporated counties · May 2026