A look into the water treatment process..

Each water authority follows strict regulations to ensure your drinking water is safe and healthy.



The process begins when raw water is drawn from the source and is filtered through a screen so as not to collect aquatic life. The water is then mixed with ferric chloride for coagulation.  When this occurs, the dissolved particles in the water bind together with the added chemicals and form larger particles, called floc.


After the coagulation forms the large floc particles, they begin to sink due to their weight. The particles then fall to the bottom of the treatment tank, this step is called sedimentation.



After the floc has settled to the bottom, the water will then move through a series of different materials such as sand, gravel and charcoal to filter out any remaining dissolved particles. 


Once the water has been filtered, a disinfectant such as chlorine is added in order to kill any remaining parasites, bacteria, and viruses before being distributed to all of the houses and businesses within the system.


Why does clean water matter?

We drink from the rivers - we are all impacted. Historically, the Ohio, Allegheny and Monongahela river valleys have been a region of famous industrial activity. Residents of the area settled here because of those work opportunities . . . ultimately finding themselves forced to live in and around the pollution their industries caused. For a century, our three major rivers were highly polluted, and we suffered under a legacy of adverse environmental impact: acid mine drainage, brownfields, oil spills, and industrial wastes. Today, these same rivers are cleaner than they have been in a century, but we still need to be alert to possible influences that adversely affect our rivers. 

Public Water Systems Fast Facts

According to the United States Environmental Protection Agency (EPA)

  • Of the approximately 155,693 public water systems in the United States, 52,110 (33.5%) are community systems and 103,583 (66.5%) are noncommunity systems, including 84,744 transient systems and 18,839 nontransient systems. 
  • Over 286 million Americans get their tap water from a community water system.
  • 8% of U.S. community water systems provide water to 82% of the U.S. population through large municipal water systems.
  • Although the majority of community water systems (78%) are supplied by ground water, more people (68%) are supplied year-round by community water systems that use surface water.

Public drinking water systems consist of community and non-community systems.

  • A community water system (CWS) supplies water to the same population year-round. It serves at least 25 people at their primary residences or at least 15 residences that are primary residences (for example, municipalities, mobile home park, sub-divisions).
  • Non-community water systems are composed of transient and non-transient water systems.
  • Transient non-community water systems (TNCWS) provide water to 25 or more people for at least 60 days/year, but not to the same people and not on a regular basis (for example, gas stations, campgrounds).
  • Non-transient non-community water systems (NTNCWS) regularly supply water to at least 25 of the same people at least six month per year, but not year-round (for example, schools, factories, office buildings, and hospitals which have their own water systems).

The EPA is responsible for the nation's drinking water regulation. To learn more, visit the EPA's Public Drinking Water Systems page.


Top Causes of Public Drinking Water Outbreaks

According to the Centers for Disease Control and Prevention

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is a microscopic parasite that causes the diarrheal illness known as giardiasis. Giardia is found on surfaces or in soil, food, or water that has been contaminated with feces (poop) from infected humans or animals. [more]

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Legionnaires' disease is caused by a type of bacterium called Legionella. The bacterium is named after a 1976 outbreak, when many people  suffered from this disease, a type of pneumonia (lung infection). [more]

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Norovirus is a very contagious virus. You can get norovirus from an infected person, contaminated food or water, or by touching contaminated surfaces. The virus causes your stomach or intestines or both to get inflamed. [more]


Shigellosis is an infectious disease caused by a group of bacteria called Shigella. Most who are infected with Shigella develop diarrhea, fever, and stomach cramps starting a day or two after they are exposed to the bacteria. [more]


Campylobacteriosis is an infectious disease caused by bacteria of the genus Campylobacter. It is one of the most common causes of diarrheal illness in the United States. Many cases go undiagnosed and is estimated to affect over 1.3 million persons every year. [more]

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Copper is a metal that occurs naturally in the environment. Low levels of copper are essential for maintaining good health. High levels can cause harmful effects such as irritation of the nose, mouth and eyes, vomiting, diarrhea, stomach cramps, nausea, and even death. [more]


Salmonella germs have been known to cause illness for over 100 years. The Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. [more]

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Hepatitis A

Hepatitis A is a liver disease that results from infection. It can last a few weeks to a severe illness lasting several months. It spreads when a person ingests fecal matter, from contact with objects, food, or drinks contaminated by the feces or stool of an infected person. [more]



Cryptosporidium is a microscopic parasite that causes the diarrheal disease "Crypto". While this parasite can be spread in several different ways, water is the most common method of transmission. It is one of the most frequent causes of waterborne disease among humans in the US. [more]


E. coli bacteria normally live in the intestines of people and animals. Some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract. [more]


For a complete listing of water-related surveillance data, see CDC’s Surveillance Reports for Drinking Water-associated Disease & Outbreaks.