A raw ground water source sample tested positive for E. coli at a well in Alamo Heights.
The well was immediately removed from service, and the water is considered safe to drink. The Alamo Heights Water System don't plan to issue a boil water notice.
According to a news release, the discovery was made Thursday at a well at East Fairoaks and Vanderhoeven Drive.
AH Water System officials said all raw water is treated before entering the distribution system as finished water for human consumption.
Officials will conduct an investigation into the possible source of bacteria from the test.