Treating Water

American Water’s treatment and delivery of water is an intricate and involved process. From the moment water begins the journey from its source through our highly sophisticated plants, into underground pipes and to its final destination, our teams of professional scientists and plant operators oversee its passage. We closely monitor its movement and quality, testing it frequently.

Each year, we conduct nearly one million tests and measurements using the most advanced technology and equipment available. Our scientists test water samples from across the country to protect against viruses, microbes, hazardous chemicals, algae, metals, minerals and other potential contaminants.

We’ve earned national acclaim for tests conducted to detect and fight Cryptosporidium, a dangerous parasite found in lakes and rivers that can cause serious gastrointestinal illness. Since 1993, American Water's scientists have been awarded three patents for Cryptosporidium research.

From the time source water from a lake, stream or reservoir enters one of our treatment plants, until it flows through your tap, it goes through five basic treatment steps:

Coagulation
Alum and other chemicals are added to water to form tiny, sticky particles called “floc,” which attract dirt and other particles suspended in water.

Sedimentation
The heavy floc particles settle to the bottom of treatment tanks, allowing for their separation from the water.

Filtration
The water passes through filters of sand, gravel and charcoal to help remove even smaller particles.

Disinfection
Chlorine is added or other disinfection methods are used to kill bacteria or other microorganisms in the water.

Storage
Water is placed in a closed tank or reservoir to allow for disinfection. Water then flows through pipes to homes and businesses in the community.