People in part of southern Prince George’s County should continue to boil their tap water until at least Friday, when test results are expected to determine if the water is safe to drink, utility officials said Thursday.

The boil-water advisory could be lifted sometime Friday if tests reveal no bacteria or other contaminants, according to the Washington Suburban Sanitary Commission.

WSSC issued the advisory as a precaution Wednesday morning after a 12-inch pipe broke in Piscataway Creek during Tuesday’s heavy rains, utility officials said. A pipe break can cause the water system to lose pressure, which could allow contaminants to seep in.

WSSC spokeswoman Lyn Riggins said multiple samples of water from various locations will undergo two rounds of testing. The section of broken pipe has been isolated, which allowed the utility to divert water around it, so no one has a dry tap, she said.

Riggins said the utility appreciates the inconvenience and economic impacts of the advisory, particularly on businesses such as restaurants.

“We’ll lift it as early as possible, as soon as we get the results of the tests,” she said.

The advisory covers Accokeek and parts of Fort Washington and Piscataway — east of Indian Head Highway, west of Piscataway Road and south of Palmer Road down to the Charles County line.

WSSC’s Web site has an interactive map that shows whether a particular address is in the affected area. People who lost water Tuesday night are not in the boil-water zone, WSSC officials said. About 10,000 homes and businesses are affected.

People in the advisory zone should continue to boil their tap water before drinking it, preparing food, making ice, serving to pets or washing dishes by hand, WSSC officials said. Water should be brought to a rolling boil for one minute and cooled before using.

The pipe, which dates to 1970, is in Piscataway Creek. Because the creek is swollen from Tuesday’s heavy rains, Riggins said, crews will wait for the water to recede before making repairs. The utility must follow certain environmental regulations when working on pipes in creek beds, she said.

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