Waterborne Diseases

Waterborne illnesses are caused by pathogens, including bacteria, viruses and parasites that are spread through the water. Exposure to contaminated water may occur from drinking or household water or from recreational water. Symptoms of waterborne illness from ingested pathogens include diarrhea, fever, nausea and vomiting.

About Waterborne Diseases

Waterborne disease refers to infections caused by pathogens, including bacteria, viruses, and parasites, that spread through water. People exposed to contaminated water may develop a waterborne illness, which describes the symptoms a person experiences when they become sick.

Exposure to contaminated water can occur through:

  • Drinking water
  • Household water use
  • Recreational water activities

Waterborne Illness Symptoms

People with a waterborne disease may experience a waterborne illness with symptoms that include:

  • Diarrhea
  • Fever
  • Nausea
  • Vomiting

Symptoms may range from mild to severe, depending on the pathogen and the individual.

How Waterborne Disease Spreads

There are three main ways waterborne disease can spread and cause waterborne illness:

  1. Swallowing contaminated food or water
    Many waterborne diseases are spread when people eat or drink contaminated food or beverages.
  2. Person-to-person or environmental contact
    Some waterborne diseases can spread through contact with infected people, contaminated animals, or contaminated environments.
  3. Breathing contaminated water droplets
    Certain waterborne diseases, such as those caused by Legionella, may occur by inhaling aerosolized water droplets from sources like fountains, misters, or showers.

Common Waterborne Disease Pathogens

Bacteria

Bacterial pathogens that can cause waterborne disease include:

  • Legionella
  • Campylobacter
  • Escherichia coli (E. coli)
  • Shigella
  • Salmonella
  • Pseudomonas
  • Vibrio

Viruses

  • Viral pathogens that can cause waterborne disease include:
  • Norovirus
  • Hepatitis A

Parasites

Parasitic pathogens that can cause waterborne disease include:

  • Cryptosporidium
  • Giardia

Learn More

External Link Disclaimer:
You are now leaving the Tennessee Department of Health website. The department is not responsible for the content of external websites.

For more information about waterborne disease, waterborne illness symptoms, and specific pathogens, visit the Centers for Disease Control and Prevention (CDC) Drinking Water webpage.

Contact Information

For questions or additional information about waterborne disease or waterborne illness, please contact:

Communicable and Environmental Diseases and Emergency Preparedness (CEDEP)
Main Line: (615) 741-7247

Related TDH Programs

Legionella

Legionellosis is an infection caused by Legionella bacteria. There are two types of legionellosis:

  • Legionnaires’ disease, a serious lung infection (pneumonia)
  • Pontiac fever, a milder illness

People can become sick with legionellosis by breathing in small water droplets that contain Legionella bacteria.

Where Legionella Is Found

Legionella bacteria grow naturally in water. The bacteria can grow and spread in a water system that is not properly maintained.

Outbreaks of legionellosis are most commonly associated with large or complex water systems, including those found in:

  • Hospitals
  • Long-term care facilities
  • Hotels
  • Other buildings with complex plumbing or aquatic systems

Trends in Legionellosis

The number and rate of reported legionellosis cases have been increasing.

Investigation Spotlight

Hotel Aquatics–Associated Outbreak (2017)

In 2017, public health officials investigated a large outbreak of legionellosis linked to a hotel aquatics facility in western Tennessee.

Learn more by reading the CDC Morbidity and Mortality Weekly Report (MMWR) article on the Tennessee legionellosis outbreak.

Legionella Fact Sheets

The following fact sheets provide guidance for different settings and populations:

Useful Links and Resources

Harmful Algal Blooms

Blue-green algae, also called cyanobacteria, are a natural part of healthy water ecosystems. However, during the summer months, when water is:

  • Warm
  • Slow-moving
  • Low in oxygen
  • High in nutrients

Cyanobacteria can grow rapidly and take over a waterbody. This rapid growth is known as a harmful algal bloom (HAB).

What Harmful Algal Blooms Look Like

Harmful algal blooms may cause the water to:

  • Turn green, blue-green, or reddish-brown
  • Smell bad or have an unpleasant taste
  • Form foam, mats, or scum on the water’s surface

Health Concerns

In certain circumstances, cyanobacteria can produce cyanotoxins, which may be harmful to people and animals. The exact conditions that cause cyanobacteria to produce toxins are not fully understood.

Frequently Asked Questions

The following frequently asked questions provide information about harmful algal blooms, including health effects, exposure risks, prevention, and reporting in Tennessee.

People and animals exposed to harmful algal blooms (HABs) and the cyanotoxins they may produce can become ill. Exposure can occur when toxins are:

  • Touched (skin contact)
  • Breathed in (inhalation of water droplets or spray)
  • Swallowed (drinking contaminated water)

Illness can affect both humans and animals.

For additional information about HABs and cyanotoxin exposure, visit the Centers for Disease Control and Prevention (CDC) Harmful Algal Blooms webpage.

People and animals may be exposed to cyanotoxins by:

  • Drinking contaminated water
  • Swimming or wading in affected water
  • Participating in recreational activities in water with a cyanobacterial bloom

Exposure may cause skin irritation or respiratory irritation. Other symptoms can vary depending on:

  • The type of toxin
  • How exposure occurred
  • How long contact lasted

It is not possible to tell whether a bloom is harmful just by looking at it. Because harmful and non-harmful blooms can look similar, people should always take precautions around visible algae blooms.

To reduce the risk of illness from HABs:

  • Do not swim or wade in water that is discolored or has foam, scum, or mats of algae on the surface.
  • Do not allow children, livestock, or pets to play in or drink water that looks scummy.
  • Always supervise children closely when they are near water.
  • If you or your pets come into contact with water that may contain cyanotoxins, rinse off with fresh water as soon as possible.

Some common cyanotoxins known to cause illness in people and animals include:

  • Microcystins
  • Cylindrospermopsin
  • Anatoxins
  • Saxitoxins
  • Nodularins
  • Lyngbyatoxins

Suspected harmful algal blooms can be reported to the Tennessee Department of Health (TDH):

For more information about HAB reporting, visit the Tennessee Department of Environment and Conservation (TDEC) Harmful Algal Blooms webpage.

Resources

Drinking Water

Drinking water can come from many different sources, including:

In Tennessee, drinking water quality for public water systems is regulated by the U.S. Environmental Protection Agency (EPA) and the Tennessee Department of Environment and Conservation (TDEC).

Private Water Supplies in Tennessee

Approximately 10 percent of Tennessee households rely on a private water supply. Private water sources may include:

  • Wells
  • Springs
  • Rainwater collection systems
  • Lakes or other surface water

For more information about private water supplies, visit the Healthy Homes webpage and review the Drinking Water information.

What is Considered a Private Water Supply?

The regulatory definition of a private water supply is based on how many people are served and for how long.

A water system is considered private if it:

  • Serves 1 to 14 households or service connections, and
  • Serves fewer than 25 people for less than 60 days per year

If a water source:

  • Has 15 or more service connections, or
  • Routinely serves 25 or more people for 60 or more days per year

It must be registered as a public water system with the TDEC Division of Water Resources.

Drinking Water Quality and Testing

In Tennessee, there are no regulations for private drinking water quality. However:

  • Water well construction standards are regulated by the TDEC Division of Water Resources
  • Individuals using private water supplies are encouraged to:
    • Test drinking water annually for pathogens
    • Test at least every other year for chemical contaminants
    • Test more frequently if nearby land use includes current or former industrial activities

Water Treatment for Private Water Supplies

Water treatment systems may be installed to improve drinking water quality in private water supplies. When adding a treatment system, TDH recommends:

Learning More About Private Drinking Water Systems

The Tennessee Department of Health (TDH) supports efforts to better understand private drinking water systems through funding from the CDC National Center for Environmental Health Capacity Program and the Safe Water Program.

Additional information is available through the TDEC Water Supply Program. 

Protecting Tennessee's Water 

Tennessee depends on clean and healthy water. Everyone can take steps to help protect water resources in their community.

Learn more by exploring the following resources developed by the Tennessee Nature Conservancy and the Tennessee Department of Environment and Conservation (TDEC):

  • TNH2O Report – A statewide report on Tennessee’s water resources and future water needs
  • TNH2O StoryMap – An interactive map that highlights water challenges and conservation efforts across Tennessee

Resources for Safe Water

Private Wells After Flooding

Water Testing

Manuals and Guides

National and Academic Resources

Recreational Water

Recreational water includes water used for fishing, boating, playing, swimming, or wading. Exposure to recreational water can occur in many settings and may lead to illness or injury.

There are two main types of recreational water: treated and untreated.

Types of Recreational Water

Treated Recreational Water

Treated recreational water undergoes filtration and disinfection. Examples include:

  • Swimming pools
  • Hot tubs and spas
  • Water parks and amusement parks
  • Splash pads
  • Interactive fountains

Untreated Recreational Water

Untreated recreational water does not receive filtration or disinfection and naturally contains microorganisms from the environment. Examples include:

  • Springs
  • Streams
  • Ponds
  • Lakes
  • Rivers
  • Oceans

Accidental swallowing of either treated or untreated recreational water may result in illness from pathogens or chemical contaminants.

Recreational Water Illness

Recreational water illness can occur when people are exposed to contaminated water. Some of the most common illnesses linked to recreational water are caused by parasites and bacteria, including:

  • Cryptosporidium
  • Giardia
  • Pseudomonas
  • Naegleria

Skin infections have also been associated with recreational water exposure.

Investigation Spotlight

Untreated Well Water Outbreak (2018)

In 2018, TDH investigated a large outbreak involving multiple pathogens at an outdoor adventure facility in eastern Tennessee. Visitors drank water from an untreated well and later became ill. Testing identified E. coli and coliform bacteria, indicating contamination.

Legionellosis Outbreak Linked to a Hotel (2017)

In July 2017, TDH investigated a large outbreak of legionellosis linked to a hotel in western Tennessee. A total of 92 people became ill. Illness was associated with time spent in or around the aquatic area, including the outdoor pool and hot tub. Water testing confirmed the presence of Legionella bacteria.

Splash Pad–Associated Salmonellosis (2014)

In 2014, TDH investigated an uncommon outbreak of salmonellosis. A common risk factor among many cases was water recreation at a splash pad. This investigation led to a statewide survey of splash pad water quality and patron behaviors.

Protecting Tennessee's Water

Tennessee depends on clean and healthy water. Everyone can take steps to protect water resources in their community.

Learn more through the following resources developed by the Tennessee Nature Conservancy and the Tennessee Department of Environment and Conservation (TDEC):

  • TNH2O Report – A statewide overview of Tennessee’s water resources
  • TNH2O StoryMap – An interactive map highlighting water challenges and conservation efforts

Water Safety: Drowning Prevention

Drowning is the fifth leading cause of unintentional injury death in the United States. Approximately 10 people die from accidental drowning each day. Nonfatal drowning can result in long-term disabilities due to brain injury.

Risk factors for drowning include:

  • Inability to swim
  • Lack of fencing around pools
  • Lack of supervision
  • Not wearing a life jacket
  • Alcohol use
  • Seizure disorders
  • Location of water activity (pool, lake, river, or ocean)

For more information, visit:

How to Prevent Drowning

To reduce the risk of drowning:

  • Learn basic swimming skills and cardiopulmonary resuscitation (CPR)
  • Closely supervise children in and around water
  • Require life jackets for children near water
  • Completely fence pools with secure, self-closing gates

Safe Water Sports

Tennessee’s lakes, rivers, streams, and reservoirs offer many opportunities for boating and water sports. While enjoyable, these activities can increase the risk of injury or drowning.

For more information, visit the CDC Safe Boating webpage.

Tips for Staying Safe During Water Activities

  • Always wear a life jacket
  • Take a boating safety course
  • Avoid alcohol while boating or participating in water sports
  • Be aware of carbon monoxide risks
  • Schedule a Vessel Safety Check (VSC)
  • Monitor weather conditions
  • Never go on the water alone

Life Jackets and Water Safety

Life jackets help prevent drowning and reduce the risk of injury. Life jackets should:

  • Be approved by the U.S. Coast Guard
  • Fit properly based on size and weight
  • Be appropriate for the activity
  • Be inspected regularly for damage

For more information, visit the U.S. Coast Guard or American Red Cross websites.

Who Should Wear a Life Jacket?

  • Children and weak swimmers near or on water
  • Anyone participating in water sports or in open water
  • Anyone near cold or icy water

This Page Last Updated: March 26, 2026 at 3:42 PM