US Open 2017: Fans given bottled water after E COLI found in drinking fountain.
Nobody has been reported ill after drinking from the hydration facility during practice days at the second major of the year, and it was shut off on Thursday morning.
"The Washington Ozaukee Public Health Department notified the USGA that it identified evidence of E coli bacteria from a sample from one hydration station near the 12th hole at Erin Hills golf course," tournament organisers the United States Golf Association (USGA) said in a statement.
"The water line to the hydration system was disconnected immediately and bottled water was provided to guests while we waited for the preliminary results to be confirmed by the public health department.
"The safety and security of our guests is of paramount importance to the USGA.
"Out of an abundance of caution, we will offer all guests complimentary bottled water at all four hydration stations throughout the duration of the championship."
E coli bacteria can cause various forms of illness, most commonly sickness and diarrhoea, but the consequences can be even more severe.
The tournament got underway on Thursday without delay despite the incident with Rickie Fowler shooting the lowest score on day one.
The American carded a bogey-free 65 to finish the day -7 and lead the field by one shot.
World No2 Rory McIlroy meanwhile struggled and despite recording an eagle at the second, he finished six shots over par well off the pace.