The protest took place at the Nongsa Digital Park, which is part of Batam's push to become a regional digital hub. Residents carried empty plastic bottles and jerry cans, shouting "Water! Water!" as they entered the compound.
Dewi Susanti, a resident of the Bakau Serip village, told the BBC that her household had not received a single drop from the tap in three months. "Our water supply had been reliable until the data centres came," she said. Her village now depends on tanker trucks that dispense "dirty, cloudy and smelly" water.
Batam's water utility told the BBC it was working to improve supply but did not comment on whether the disruption was linked to demand from the data centres. BP Batam, the agency overseeing trade and industry on the island, denied allegations that water meant for homes was being channelled to data centres, blaming the shortages instead on a prolonged dry spell.
The protest follows earlier demonstrations in August and September. In response, authorities told companies opening data centres on Batam that they must build their own desalination plants rather than rely on reservoirs for freshwater.
However, locals remain concerned about competing with servers for water. Agus Hasan, a professor at the Norwegian University of Science and Technology, noted that reliable data on data centre water use in Indonesia is scarce, partly because companies treat it as proprietary information. "We should build [data centres] rationally, transparently, and responsibly, and insist on seeing the numbers," he said.