Rahul Somvanshi
Colt Data Centre Services and RMZ have begun construction of Mumbai 3, a 64MW data centre at their Navi Mumbai campus, after signing an unnamed hyperscale customer. The project’s central environmental question is not whether cooling will matter—it will—but how much water and electricity the facility will use once it begins serving high-density AI and computing workloads.
The companies say the facility will be powered entirely by renewable energy and use hybrid cooling: conventional air cooling alongside direct liquid-to-chip cooling. They also say a closed-loop cooling system is designed to enable near-zero wastewater. Those commitments could reduce discharge and avoid some of the water losses associated with once-through cooling.
The key water number is still missing
“Near-zero wastewater” is not the same as zero water consumption. Closed-loop systems can reduce blowdown—the water discharged to control mineral concentration—but facilities may still need water for initial filling, maintenance, treatment and other operations. Colt and RMZ have not published Mumbai 3’s projected annual water consumption, water-usage effectiveness target, cooling-water source or a site-specific water-risk assessment.
That makes it impossible to calculate the project’s water demand or compare it with local supply. The company announcement confirms the renewable-energy and closed-loop design claims, but does not provide the operating figures needed to test them.
The power footprint is also substantial. Mumbai 3 is planned for 64MW, and the Navi Mumbai campus could reach 148MW at full development. The wider Colt DCS–RMZ venture aims for 250MW across Mumbai and Chennai. A renewable-energy claim is meaningful only if it is backed by clear sourcing arrangements, matching methodology and evidence of additional clean generation rather than an unexamined contractual label.
What public disclosure should include
For a project of this scale, useful reporting would disclose annual water withdrawals and consumption, the proportion from potable, recycled or other sources, water-use effectiveness, wastewater volumes, power-usage effectiveness and the precise renewable-energy procurement model. It should also explain how the cooling system performs during the hottest and most humid periods, when cooling demand is highest.
Will Mumbai 3 harm local water supplies? The available information does not establish that. Nor does it allow the opposite conclusion. The project’s stated design may limit wastewater, but the lack of published consumption data leaves residents and regulators unable to assess the local water burden.
AI infrastructure can be built with lower water and emissions impacts, but those outcomes must be measured, not assumed. Mumbai 3’s environmental case will depend on transparent operating data after construction, not only on design claims made before it opens.
