DeKalb County residents will see an increase in their water bills starting in January.

The 11 percent increase that took effect Jan. 1 is part of a three-year plan to raise rates to pay for a $1.35 billion overhaul to the county’s aging water and sewer system. Rates increase by 11 percent in 2013 and 2014 as part of that plan.

The increase translates into about $6.43 more a month for the average customer using 5,000 gallons of water monthly. DeKalb water rates last increased in 2008, when they went up by 16 percent.