Today in the United States, public water systems large and small provide their customers with the highest quality drinking water in the world. Before disinfection became a common practice, widespread outbreaks of cholera and typhoid were frequent throughout the United States. These diseases are still common in less developed countries, but have largely disappeared in the United States as chlorine and filtration became widely used about 80 years ago.

Your tap water is treated to meet strict drinking water standards that are established by the State and Federal Government.  The standards are established for the protection of the health of all citizens.  The EPA require that we monitor for over 80 different contaminates.

Typical Water Treatment Processes

There are many methods of treating water so that it is fit for potable uses. Depending on the source water available to many public water suppliers, they many require several techniques :


Pretreatment is used to kill disease-causing organisms and help control taste and odor causing substances. A pretreatment chemical could be any number of oxidants or disinfectants. Ozone, hydrogen peroxide, potassium permanganate and chlorine are all commonly used in water treatment.


The purpose of aeration is to “off-gas” taste and odor causing substances by passing large quantities of air through the water. This is accomplished by pumping air through a series of diffusers placed on the bottom of the storage basins, which causes the water to “boil.” The resulting air bubbles carry off the most volatile of the taste- and odor-causing organics.


 Coagulation starts immediately after flash mixing and is facilitated by the flocculation process. Flocculation is a gentle mixing of coagulated raw water. This mixing allows particles now “sticky” from the addition of coagulant, to gather to form larger, heavier particles called “floc.”

Flash Mixing

 The flash mix, or rapid mix process, occurs just after coagulation chemicals are added to the raw water. Coagulation chemicals are used to attract particles together that will not readily settle or filter out of the water. Some examples of coagulation chemicals include aluminum sulfate and various polymers.


The sedimentation process settles out larger suspended particles and the floc created through the coagulation/flocculation process. As the raw water flows very slowly through the sedimentation basin, heavy particles fall to the floor while the water overflows the basin and is channeled into filters. The particles resting on the floor of the basin are moved into a sludge basin for eventual disposal.


 Through the filtration process, any remaining particles are removed from the raw water. The water may be filtered through layers of sand, gravel and/or coal. The raw water travels through the various filter materials and out into the treatment plant reservoir. Some examples of filter materials include mixed media (layers of various sizes of gravel, high-density garnet, sand and anthracite coal), diatomaceous earth, and granular activated carbon (GAC).


The finished water from the treatment plant may be disinfected as it leaves the reservoir and enters the distribution system. Disinfection ensures unwanted bacteria and organisms have been eliminated and helps discourage any further growth of disease-causing organisms in the drinking water.

How We Treat Our Source Water

Our deep bedrock wells and the water of the Carrabassett River’s West Branch provide us with quality source water that requires minimal treatment. Actually, the majority of our source water comes from the deep bedrock wells and requires no treatment at all. To meet high system demands we filter the pristine waters from the West Branch of the Carrabassett River. We filter this water through a Kinetico Macrolite filter system that requires no pre filter treatment. Public water systems in Maine are not required to disinfect ground water(our wells), only surface water (Carrabassett River). Because surface water combines with ground water throughout our distribution system, we inject the minimum sodium hypochlorite “liquid chlorine” necessary to maintain trace chlorine residual throughout our distribution system to ensure the safety of our community.