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How Water is Treated

Charlotte-Mecklenburg Utilities uses a very common process in treating and purifying water for Charlotte and Mecklenburg County. The process is broken into five steps: coagulation, flocculation, sedimentation, filtration and disinfection.

During coagulation, liquid aluminum sulfate (alum) is added to untreated water (raw water). When mixed with the water, this causes the tiny particles of dirt in the water to stick together or coagulate.

Paddles in these large tanks stir the alum and water mixture, causing them to stick together and form large, heavier particles called floc.

How Water is Treated at a Water Treatment PlantSedimentation
As the water and the floc particles progress through the treatment process, they move into sedimentation basins where the water moves slowly, causing the heavy floc particles to settle to the bottom. Floc which collects on the bottom of the basin is removed from the water.

From the sedimentation basin, the water flows through a filter designed to move any remaining particles left in the water. The filters are made of layers of sand and gravel.

Once water is filtered, chlorine is added to kill any germs or contaminants.

How Water is Treated from lake to tap

Following this process, the treated water enters the distribution system and is pumped through more than 4,000 miles of underground pipes to each home and business. Water treated by Charlotte-Mecklenburg Utilities is sampled and tested throughout the treatment process. Samples also are collected and tested several times daily throughout the distribution system.  To learn more about water quality, check out our frequently asked questions.