Colonial Beach residents say they were notified Tuesday morning that the water from their faucets could make them sick.
People who live in the area have been told to boil their water before drinking it. Boiling kills the bacteria and other organisms in the water.
Town leaders say a water sample tested positive for E. coli on July 8, almost two weeks before the warnings were made.
A boil water alert means that boiled or bottled water should be used for drinking, making ice, brushing teeth, washing dishes, and food preparation until further notice. Bring the water to a boil, let it boil for three minutes and let it cool before using, or use bottled water.
E. coli can cause nausea, cramps, diarrhea and/or headaches.
Town leaders say they are flushing pipes, increasing chlorination,and performing more follow-up tests to fix the problem.
The notice uploaded to the county website said to continue boiling water until they residents the tests show no bacteria.