Alameda city officials issued a two-day alert Tuesday evening warning residents in the Alameda Point neighborhood not to drink tap water.
The alert comes after the East Bay Municipal Utility District found evidence of quality issues in the Alameda Point drinking water system, probably caused by a "cross-connection" between a drinking water line and an irrigation line.
It's not clear when — or how — the cross-connection occurred or what specifically was detected that triggered the warning.
Residents were advised not to drink water from faucets or use tap water to brush their teeth, wash dishes, bathe, cook or give to their pets.
As crews work to restore water quality to the distribution system, the city is distributing bottled water at the Alameda Point Collaborative office at 677 W. Ranger Ave.
Water bottles will be left outside for pickup 24 hours a day for the 267 households and 60 businesses potentially affected by the problem.
Officials said the issue is confined to Alameda Point and stems from the old infrastructure at the former Naval Air Station Alameda, which closed in 1997. Water quality elsewhere in the city is unaffected.
About 10 p.m., officials said the water quality was improving.