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.

Coagulation
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.

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

Sedimentation
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.

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

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

Following this process, the treated water enters the distribution system and is pumped through 3,900 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.