North Carolina alone is forecast to get 9.6 trillion gallons, enough to cover the Tar Heel state to a depth of about 10 inches (25 centimetres).
"I'm anxious about what I might find when I go home, though", she said.
Spokesman Howard Fowler said restoration could take "weeks instead of days", even though 20,000 workers, including crews from outside the area, were standing by.
People in areas vulnerable to the unsafe hurricane, particularly those in coastal regions, have fled ahead of the storm.
Florence's eye could come ashore early Friday around the North Carolina-South Carolina line.
Up to 1.7million residents on the eastern seaboard have been scrambling to evacuate their homes as government officials warned the hurricane would deliver a "Mike Tyson punch" to South Carolina, North Carolina and Virginia.
"Hurricane Florence is powerful, slow and relentless", North Carolina Gov. Roy Cooper said.
Hurricane Florence slowed dramatically as it approached shallower waters along the coast, dropping from a Category 4 hurricane with 130 miles per hour (209 km/h) winds on Wednesday (Sept. 12) to a Category 2 Thursday. The hurricane center described the storm surge as "life-threatening".
Florence has been downgraded to a Category 1 storm, but forecasters say it is still capable of delivering a lethal punch.
"To those in the storm's path, if you can hear me, please stay sheltered in place", he said at a news conference in Raleigh, adding that Florence would "continue its violent grind across the state for days".More news: Windows 10 Test Halts Competing Browser Installs, Suggests Edge Instead
Florence made landfall as a Category 1 hurricane at 7:15 a.m.at Wrightsville Beach, a few miles east of Wilmington, not far from the SC line, coming ashore along a mostly boarded-up, emptied-out stretch of coastline.
The National Hurricane Center said the storm will eventually push westward and make a right hook to the northeast over the southern Appalachians, moving into the mid-Atlantic region and New England as a tropical depression by the middle of next week.
More than 370,000 people were without power in North Carolina early on Friday, state officials said.
"(It's) very eerie, the wind howling, the rain blowing sideways, debris flying", said Sandie Orsa, of Wilmington, who fears splintering trees will destroy her home. Calls for help kept coming in as the wind picked up and the tide arrived, said city public information officer Colleen Roberts.
Authorities said more than 60 people, including many children and pets, had to be evacuated from a hotel in Jacksonville, North Carolina, after strong winds caused parts of the roof to collapse.
More than a million people were ordered to leave the coasts of the Carolinas and Virginia, with over 12,000 taking refuge in emergency shelters.
The impact of Florence will be widespread, with destructive winds, life-threatening storm surge, unsafe surf, torrential rainfall, flooding and the potential for tornadoes. She said a hurricane has a way of bringing everyone to the same level.
"The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves, " it said.