This potentially harmful bacteria could have entered through cracked pipes, heavy rains could have delivered it to the town's water source or the water wasn't treated properly.
Whatever the cause, everyone in town is carefully monitoring what they're drinking. Residents in Woodville are loading up on bottled water.
E. coli was found in their water supply last Thursday leading to a boil advisory.
One convenience store owner says he's had to restock his shelves several times this weekend.
Robbie Rodriguez says he wants to make sure his family's safe from possible infection. "This should be the last one if it's not then I'll come back at like midnight and fill it up for my grandma."
E. coli is a bacterium commonly found in human and animal digestive tracts. Some strains can cause diarrhea, nausea and if untreated, possible death.
Ralph Gutierrez, Woodville Public Utility manager, says "I immediately started emergency chlorination and I went out and I flushed the whole system."
Gutierrez sent out the boil advisory to residents warning them to not to drink or wash dishes with water from the tap.
E. coli presents serious health threats to children, seniors, and people with weak immune systems.
The E. coli threat was a concern for Richard Wilson. Out of town family's visiting to celebrate his kid's 4th birthday party. "Are they going to get sick? Or anything might happen to them you know. I am just kind of worried."
Gutierrez says Woodville's one of the few remaining towns in California that isn't required by state regulations to use chlorine as a form of water treatment.
So far there have been no reports of anyone getting sick.
Gutierrez is waiting for test results next week to confirm drinking water is safe for residents. Until then the boil advisory will remain in effect.