Tap water in an affluent enclave near Seattle has tested positive for E. coli bacteria for the second time in a week, prompting Washington state health officials to close restaurants on Friday and urge residents to boil water before using it, according to The Associated Press.
The bacteria first showed up in the water supply on Mercer Island, a Seattle suburb on Lake Washington, on Sept. 26, forcing area schools to close on Monday as health officials collected thousands of samples in an effort to locate the source of the contamination, the AP reported.
The alert was lifted earlier this week, but a water sample test on Thursday indicated the presence of E. coli, a fecal coliform bacteria that indicates the presence of sewage or animal waste in the water supply, according to health officials, according to the AP.
Friday's advisory to boil water on Mercer Island affects about 24,000 people and dozens of businesses, the AP reported. Mayor Bruce Bassett apologized to residents, calling the situation "exceedingly unfortunate."
Mercer Island schools were open on Friday, but health department officials ordered restaurants and cafes to close, according to the AP.
Bottled water was being distributed at community centers and schools, the AP reported.
"As of today, (there are) still no confirmed cases of E. coli illness," Mercer Island officials said in a statement, according to the AP. The source of the possible contamination remained unknown.
According to the Centers for Disease Control and Prevention, most strains of E. coli are harmless but others can cause illness, the AP reported.
Mercer Island buys its water from Seattle Public Utilities, which provides water to about 1.5 million people in the Seattle area, according to the AP. The tap water is chlorinated, which normally kills the bacteria.
The utility said in statement the contamination was "isolated" to Mercer Island, the AP reported.
"All other water provided by SPU has tested safe for drinking," the statement said, according to the AP.
Investigators were collecting samples from all over the island and inspecting water lines, tanks and other supply systems, the AP reported.
In September, a 4-year-old girl from Lincoln City, Oregon, died, a 3-year-old girl from Lynden, Washington, died and a 5-year-old Tacoma boy was hospitalized after they were infected with a strain that can lead to kidney failure, according to the AP.
In 1999, about 1,000 people fell ill near Albany, New York, after consuming food and beverages containing water from a well that was contaminated. An elderly man and a child died, the AP reported.
