Nonetheless, University officials said precautions still are being taken to conserve water.
On Friday, the Orange Water and Sewer Authority started enforcing Stage 2 water restrictions in response to the worst drought the area has ever experienced.
Stage 2 restrictions limit certain kinds of outdoor water use. For instance, residents are limited to watering with hoses or sprinklers one day per week.
The average weekly water use in August was about 11 million gallons until last week, when it went up to 12.7 million gallons.
Greg Feller, OWASA's director of public affairs, said students' arrival to Chapel Hill is not the only factor in the past week's increase.
Because there has been so little rain, outdoor water use has increased, Feller said. "The hotter and dryer it is, the more water is used," he said.
Carolyn Elfland, UNC's vice chancellor for campus services, said there was no substantial rainfall the week before students came back, a possible reason for the increase.
"When it doesn't rain, the consumption goes up anyway," Elfland said. "Consumption is more tied to rain than to students coming back."
Feller cited a record day in June, when most students had left campus, on which about 16 million gallons of water were used -- 3 million gallons more than the daily average for that month. He said that was a clear example of why he thinks students on campus haven't affected recent water usage.