Drinking Water Facilities

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Gwinnett County operates and maintains two of the largest and most technologically advanced water treatment plants in the state of Georgia. The Lanier Filter Plant and the Shoal Creek Filter Plant combined can produce more than 200 million gallons of drinking water a day.

We also maintain 10 water storage tanks located throughout the county with a combined capacity of nearly 120 million gallons of water, ensuring a continuous water supply for human consumption and firefighting.

The Lanier Filter Plant and the Shoal Creek Filter Plant use ozone and biofiltration technologies to treat the water from Lake to drinking water standards. Our state-certified staff works year-round to ensure clean water for the county using continuous computer monitoring and in-person laboratory analysis every hour of every day. There have been no major violations of the Safe Drinking Water Act at either plant—a testament to our staff’s hard work and dedication to protecting public health and safety.

To learn more about ozone biofiltration and the step-by-step process we use to clean water in Gwinnett County, use the drop-down menu below.

Water is withdrawn from Lake Lanier through large intake pipes. The lake water is then stored in equalization basins or reservoirs at each facility to provide process flow rate stabilization. Simply put, these lake water-holding basins balance the rate of water production depending on the county’s current water supply needs.

The initial step in the water treatment process is ozonation. Ozone is created by combining pure gaseous oxygen and electricity through a series of complex operating systems. Its primary purpose is disinfection as well as oxidation of compounds to improve water clarity, smell, and taste.

In the next step of the treatment process, chemicals called coagulants are introduced and the water is rapidly mixed so as to form "sticky" receptors which cause small particles to clump together. “Rapid mix” is just as it sounds: rapidly mixing the water to blend the chemicals together quickly. Flocculation involves successively slower mixing to further develop the suspended particles or "floc" that is captured by filtration in the succeeding step.

Filtration is the most important and regulated step in the treatment process. Our unconventional filter plants use direct filtration, which means we omit a sedimentation phase seen in most water treatment plants. We are able to do this because of the exceptionally clean and unchanging source of water from Lake Lanier.

Our filters are comprised of large rectangular vessels filled with a dual media of anthracite carbon and sand.  The particles created in the previous treatment processes are physically captured or intercepted through adsorptive and absorptive forces within the filter media. There is also a biological component, where the “biomass”—a group of tiny organisms—consumes organic and inorganic compounds broken down by the ozonation process.

After filtration, the water receives a final treatment of beneficial or "finishing" chemicals including lime (pH control), fluoride (dental health), corrosion inhibitor (pipe protection), and chlorine (disinfection).

The last step in the process is finished water storage and pumping. Water is stored at each filter plant in large tanks called clearwells before being pumped into our huge network of pipelines and supplemental storage tanks located throughout the county. Each critical step in our treatment process guarantees safe, secure, and plentiful water at every tap!

Shoal Creek Filter Plant

  • Georgia Association of Water Professionals, Plant of the Year Award
    • Award won in 2007, 2013, 2014, and 2017
    • Georgia Association of Water Professionals, Perfect Compliance Record
      • Gold Award (awarded once per year) received eight times
      • Platinum Award (awarded once every five years) received twice


Lanier Filter plant

  • GA Association of Water Professional, Perfect Compliance Record
    • Gold Award (awarded once per year) received four times

Gwinnett County’s filter plants are two of only four facilities in Georgia that use ozone in their drinking water treatment process. Ozone is a powerful oxidant (chlorine and hydrogen peroxide are also oxidants) with a much higher oxidation potential than chlorine. This oxidizing power is what gives it the ability to kill viruses, microbials, and other pathogens. It improves the clarity of the water and removes algal toxins.

Ozone also removes dissolved organics like taste and odor compounds, residuals from pharmaceuticals, and more. It breaks down these organic compounds into smaller pieces that can be used as food by the biomass on the filters during the direct filtration stage of the process.