What is The Municipal Water Treatment Process?

Municipal drinking water supplies in the United States are among the safest in the world. But a lot has to happen before safe drinking water can pour out of the kitchen tap. Water sources, including underground aquifers and surface sources like reservoirs and rivers, can become contaminated from waterborne germs, such as Cryptosporidium, E. coli, Hepatitis A, Giardia intestinalis, and other pathogens. Fortunately, SUEZ North America is an expert in the municipal treatment of drinking water. Read on if you’re curious about municipal water treatment steps.
Municipal Water Treatment Process
Nothing is more important than the safety of our customers and delivering clean water is our top priority. Our highly trained and licensed drinking water monitoring and treatment professionals work 24 hours a day, 365 days a year to provide premier service and superior quality management. Some of our treatment processes include granular activated carbon (GAC), Dissolved Air Flotation (DAF), ozone generation and UV disinfection systems.

We regularly conduct water supply quality testing before, during and after the treatment process to ensure it meets or surpasses regulatory standards, monitoring for lead, copper and corrosion. SUEZ technologies help to maintain water quality control from treatment to tap. In fact, we issue an Annual Consumer Confidence Report (CCR) for every water source we touch, demonstrating how our drinking water measures up to regulatory standards.

There are different ways to treat water for distribution to municipal customers. In general, drinking water treatment includes four key steps: coagulation and flocculation; sedimentation; filtration; and disinfection.

Coagulation and flocculation

Coagulation and flocculation are the steps by which chemicals with a positive charge are added to the water being treated. The positive charge of these chemicals neutralizes the negative charge of dirt and other dissolved particles in the water. When this occurs, the particles bind with the chemicals and form larger particles, called floc.

Coagulation typically can be accomplished through the addition of inorganic salts of aluminum or iron. These inorganic salts neutralize the charge on the particles causing raw water turbidity, and also hydrolyze to form insoluble precipitates, which entrap particles.

Coagulation can also be affected by the addition of water-soluble organic polymers with numerous ionized sites for particle charge neutralization. Flocculation can be enhanced by the addition of high-molecular-weight, water soluble organic polymers. These polymers increase floc size by charged site binding and by molecular bridging.

Sedimentation & Dissolved Air Flotation

The next step, sedimentation, is when floc settles to the bottom of the water supply, due to its weight. SUEZ will sometimes use a technique we pioneered called Dissolved Air Flotation (DAF). This is an excellent solution for clarifying water with high levels of algae and other low-density solids that cannot be removed efficiently by sedimentation.


Next comes filtration. Once the floc has settled to the bottom of the water supply, the clear water on top will pass through filters of varying compositions (sand, gravel, and charcoal) and pore sizes, in order to remove dissolved particles, such as dust, parasites, bacteria, viruses, and chemicals. SUEZ has a wide range of separation technologies designed for the treatment of drinking water. We also offer maintenance service for filters that have already been installed.


Then, after the water has been filtered, a disinfectant such as chlorine may be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the water from germs when it is piped to homes and businesses. SUEZ also offers advanced disinfection processes such as UV and ozonation.
Providing Safe Drinking Water for Municipalities
Every day we provide safe, reliable drinking water to communities across North America. Using innovative filtration, clarification and disinfection techniques, we provide millions of homes and businesses with water that consistently meets or exceeds the highest state and federal standards. And we support the towns and cities we serve, working hand-in-hand with local officials to operate, maintain and manage their complex water services.

Contact a representative to learn more about SUEZ' municipal water treatment services.