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Water Treatment Process


WT Process #2 

Water treatment is the process of purifying water. Treatment makes the water safe to drink. Because it is a good solvent, water picks up all sorts of natural pollutants. In nature, water is not always clean enough for people to drink. Today almost every city in the world treats their drinking water.

WP Operator #3



In the state of Texas, current rules and regulations have accelerated the need for more competent, skilled water utility operators who are responsible for safely and successfully producing water quality among the safest in the world. All operators at the Water Treatment Plant are certified and licensed by the Texas Commission on Environmental Quality (TCEQ), ensuring the water that reaches your home meets or exceeds current regulatory standards, at all times.

Intake #4


Intake: Water is pumped from Lewisville Lake and delivered to the treatment plant. The City of Lewisville purchases raw (lake) water from the City of Dallas. During the summer months, activated carbon is added to assist in controlling any taste and odor problems.

Chemical Addition: Liquid ferric sulfate, lime, polymer, chlorine, and ammonia are added to the water. The water and chemicals are mixed together to start the purification process. These chemicals kill microorganisms, improve taste and odor, help settle solids, and purify the water.

Coagulation and Flocculation: In the process of coagulation, ferric sulfate and other chemicals cling to particles in the water. This causes the particles to stick together and form larger particles called floc.
Clarifier #5



Sedimentation: The water and floc particles flow into a sedimentation basin. The floc settles to the bottom and is removed from the clarified water. On the left, a certified operator can be seen taking a sample of the treated water. Operators perform thousands of process control tests in their on-site laboratory each week.

Filtration: From the sedimentation basins, the water flows through filters. Filters consist of 44 inches of anthracite coal. The filters are used to remove any remaining particles in the water.

Disinfection: Small amounts of chlorine and ammonia provide disinfection of the water by killing any remaining microorganisms in the water and to keep the water safe as it travels through the distribution lines to the public.

Storage: Treated water flows into ground storage reservoirs called a clearwells. These allow time for the chlorine and ammonia to mix through in the water for proper disinfection. The reservoirs also provide a reserve supply of water for high usage periods. The City has four clearwells with a combined capacity of seven million gallons.

The water is then pumped into the distribution system lines and to the elevated storage tanks. Elevated storage tanks have a multi-fold purpose: to provide additional storage, for protection, and to supply adequate pressure to the distribution system.

NPS #7

            EST #6            

SCADA #8The System Control and Data Acquisition (SCADA) system monitors the water levels in each tank, as well as the status of the entire distribution system. A certified operator records the water levels in each overhead tank. The operators can also control the rate at which water is pumped at pump stations throughout the city, as well as all valves in the overhead storage tanks, allowing for even distribution and level control. Problems in the system can easily be detected as the SCADA System records sudden drops in water pressure or unusually high water usage.