The Department of Watershed Management confirmed a massive water main break that caused flooding and prompted water restrictions for four cities has been repaired, but it hasn’t given the all-clear just yet.

A boil advisory is still in effect for residents and businesses in some parts of south Fulton County while the department disinfects the water system and tests water for quality issues.

Flushing the system will take 1-2 hours, the department said in a statement. But collecting and analyzing water samples could take up to a day.

People in the cities of Chattahoochee Hills, South Fulton, Union City and Fairburn have experienced low water pressure since a 30-inch water main broke at Fairburn Road near Cascade Road on Monday. Department spokesman Rukiya Campbell said more than 100,000 customers are affected.

According to Fulton County Schools, 24 schools were also impacted, including one elementary school completely without water.

RELATED: 24 Fulton schools under boil-water order

Without any running water, administrators at Campbell Elementary made the decision Tuesday morning to relocate all students and staff to Palmetto Elementary for the rest of the day. Meal service, transportation home and after-school care were still expected to be provided from Palmetto. Classes in the Extended Day program were canceled, according to Principal Leah McDaniel.

The other schools remained open Tuesday with safety plans in place.

“Bottled water has been provided to all impacted schools and cafeterias are planning alternate meals that are healthy and ensure safety,” district officials said on Facebook. “Our schools have backup systems that keep our restrooms in working order.”

County officials closed the south Fulton County Government Center due to no water pressure at the facility on 5600 Stonewall Tell Road.

“Currently, the staff of the Fulton County Department of Real Estate and Asset Management is assessing what items need to be in place should issues continue through the week,” the county said in a statement.

A 30-inch water main broke at Fairburn Road near Cascade Road on Monday. JOHN SPINK / JSPINK@AJC.COM
icon to expand image

The break flooded cars and left customers of local businesses in the area stranded for hours.

South Fulton Deputy Fire Chief Wesley Stubbs told AJC.com that no lives were threatened.

Carl Long (left) and Anthony Jones with the Atlanta Department of Watershed Management work in freezing temperatures Tuesday to repair a 30-inch water main that broke Monday at Fairburn Road near Cascade Road. JOHN SPINK / JSPINK@AJC.COM
icon to expand image

— Please return to AJC.com for updates.