🧪 Will a data center poison our water table or contaminate groundwater?

This is a different question from “how much water will it use” — it’s about water quality, and it deserves a direct answer. The short version: the well-documented concern with data centers is how much water they consume, not poisoning of the aquifer, because of how their cooling actually works.

A data center is not a chemical plant. Its cooling water is “non-contact” heat-transfer water — it carries heat away from equipment and does not touch toxic process chemicals the way heavy industry does. The draft ordinance reinforces this by flatly prohibiting hazardous chemical processing, petroleum refining, and waste-disposal facilities (see Section 6 — Prohibited Uses).

Closed-loop systems don’t discharge at all. A closed-loop cooling system (like the newer designs described in our water-use answer) is filled once and recirculates the same water in sealed pipes — it isn’t dumping water into the ground.

Where chemicals are used, the wastewater is permitted and monitored — not dumped. In open evaporative cooling, treatment chemicals (such as biocides to prevent Legionella, and anti-scaling agents) are added, and the leftover “blowdown” water is discharged under a Clean Water Act (NPDES) permit, with enforceable limits and monitoring — not released into groundwater. In Kansas, that permitting is handled by the Kansas Department of Health and Environment (KDHE), which administers the NPDES program for the state: a facility that discharges to a stream or lake needs a KDHE/EPA NPDES permit, and discharge to a city sewer instead goes through the local utility’s pretreatment program.

What’s the real risk, by cooling type? Contamination risk tracks how much a design contacts water and uses treatment chemicals:

• Air-cooled (no water): essentially no water-contamination risk — there is no cooling water to treat or discharge (the trade-off is more electricity).
• Closed-loop / recirculating liquid (including chip-level): water is sealed in pipes and recirculated with little or no ongoing discharge, so there is no normal pathway to groundwater. The only risks are a contained leak/spill or proper disposal of the fluid at end of life.
• Evaporative / open cooling towers: this is where the real (but managed) risk sits. The warm tower water is treated with biocides to control Legionella bacteria, plus scale and corrosion inhibitors, and the leftover “blowdown” carries those chemicals and concentrated dissolved solids — which is exactly why it is discharged under permit and monitored, not released to groundwater. Legionella itself is mainly an airborne concern, spread by fine “drift” droplets and controlled with treatment and drift eliminators (per the CDC).
• Hybrid / “adiabatic”: mostly air-cooled, with evaporative assist only on hot days — a much smaller version of the cooling-tower risks.
• Immersion cooling: servers sit in a non-water dielectric fluid in a sealed system; no water discharge — the fluid is simply contained and disposed of properly.

The pattern is clear: the more a design leans on evaporation plus chemical treatment, the more there is to manage; air-cooled and closed-loop designs push the water-quality risk close to zero. That’s why the City intends to favor low-water cooling and most likely not permit evaporative cooling (see How data centers are cooled).

On-site fuel is contained. The realistic chemical hazard at a data center is the diesel fuel for backup generators. That is governed by EPA’s Spill Prevention, Control, and Countermeasure (SPCC) rule, which requires secondary containment and a spill-prevention plan specifically to keep oil out of soil and water.

An honest caveat: the risk is low and managed by standard permits — but it is not literally zero. Blowdown water contains treatment chemicals and dissolved solids, which is exactly why it is capped and monitored rather than released freely.

What the City can require / commit to:

• Require closed-loop cooling (which does not discharge) where practical.
• Require any discharge to go to the sanitary sewer under the utility’s pretreatment program, or under a monitored NPDES permit — never to groundwater.
• Require an SPCC spill-prevention plan and secondary containment for fuel and any on-site chemicals.
• Use the water protections in Section 13 and the proposed Section 13A to make these binding conditions of approval.