Full water pressure and clear water have been restored throughout the city’s water system, according to Charlotte Katzenmoyer, the city public works director.

The advisory issued Thursday evening, 10 hours after the water line break, is a precaution, said Mayor Charlie Smithgall, who said he drank city water throughout the day.

Whenever there is negative water pressure, the state Department of Environmental Protection requires an advisory to boil water for drinking, brushing teeth, washing dishes or preparing food.

Theoretically, negative pressure could allow groundwater or toilet water to be sucked into water pipes in buildings where there isn’t backflow prevention devices, Katzenmoyer said.

The city has been testing the seven areas since Thursday for water quality and clarity and hopes to be able to lift the boiling advisory Saturday morning, Katzenmoyer said today.

Water should be boiled by residents in these areas:

· South Duke Street to Broad Street; Broad Street to Walnut Street; and Walnut Street to Duke Street.

· Areas around Franklin & Marshall College campus and Buchanan Park — College Avenue to Harrisburg Avenue; Harrisburg Avenue to President Avenue; President Avenue to Marietta Avenue; and Marietta Avenue to College Avenue.

· Grandview Heights and Mayfair Manor.

· Hornig Road in the area of J.E. Fritz Elementary School; Sherreem Road; Lamplight Circle; Kolb Drive; Veumont Drive; Harmony Hill Drive; Lyndell Drive.

· Mission Hills off Route 272.

· Roseville, Landis Farms, Bloomingdale and Beverly estates; Eden Road north to Route 222; south of Nitrauer Elementary School.

· Bausman area — east of Millersville Pike to Pearl Street; Pearl Street to St. Joseph Street; and north of Michelle Drive to Judie Lane.

Crews worked through the night to repair a 4-foot section of 1930s-era cast iron pipe that cracked open shortly before 6 a.m. Thursday on Burle Industries property, off New Holland Avenue.

They were hindered because the pipe sits on solid bedrock that had to be removed. Though old age was probably the chief cause for the rupture, it didn’t help that the pipe did not have a gravel “cushion” around it and received decades of vibrations from the adjacent Amtrak rail line, Katzenmoyer observed.