After drawing raw water from our reservoirs, we begin what may be the most important phase of our operation—purification and treatment.
At our treatment plant, water destined for household use undergoes a three-part process that clarifies, filters, and purifies completely.
Raw water taken directly from the source often contains many harmless organic and inorganic particles in suspension. And our first processing task is to separate and remove this material. First, water drawn from our reservoirs flows into mixing tanks where operators add a special coagulant. This step helps to clear the water of relatively larger particulate material and discoloration as this agent causes organic and inorganic matter to grow into larger, heavier particles that begin to settle at the bottom of the tank. Once the majority of these particles have separated out of the water, it is ready for further processing.
Secondly, the freshly clarified water runs through a our dual media filters. Filtration further purifies and clears the water of finer particles, minerals, and organic matter and other materials that can affect color, odor, and taste. By now, the water resembles something like the water that flows from your tap, but there are still a few more steps in the process.
Once filtration clears most inorganic and organic particles, discolorations, and contaminants, we chlorinate, adding just the correct amount to eradicate any remaining microbes. Adjusting the levels as necessary, we can eliminate harmful bacteria and viruses while maintaining safe amounts of chlorine for household use—as well as to maintain the fresh taste we all expect from a cold glass of fresh water.
We also test the pH and adjust acidity, adding orthophosphate, which helps control pipe corrosion in our transmission lines and your home’s plumbing system. In a final step before pumping our water to you, and as a public health measure recommended by the American Dental Association, we add fluoride to the water supply as a defense against tooth decay delivered in every glass of water you drink.
In addition to our primary water source, our reservoirs, we operate the Kellog-Deering wellfield complex on the west bank of the Norwalk River in Norwalk, CT. Water from these four gravel-packed wells augments our reservoir supply during periods of drought and heavy water use.
The Kellogg Deering Wellfield
Purification of this water is similar to that of our surface water at the treatment plant with addition of an air-stripping process at the wellfield. This system aerates the water, allowing gases and volatiles to evaporate out, leaving clean water for our use. We then pump this vented water and add disinfecting chemicals, orthophosphate and fluoride. This treated water is then mixed with treated water from the filtration plant in the distribution system.