11 Common Waterborne Diseases: Symptoms and Prevention

An informative and practical guide to recognizing and avoiding the 11 most common waterborne diseases including cholera, norovirus, shigella, legionnaire’s disease, and typhoid fever, as well as the most effective ways in treating the water prior to consumption.

Updated: November 14, 2023
Jeremiah Zac


Water certainly is the source of life.

But with the potential to harbor pathogens that can cause serious harm to the human body, careful precautions must be taken in determining when it is safe to drink and when it isn’t.

The World Health Organization states that more than 3.4 million people die from waterborne diseases every year, making it the world's leading cause of disease and death (Berman, 2009).

The pathogens responsible for these diseases come in the form of viruses, bacteria, or protozoa, all invisible to the naked eye.

This article covers the 11 most common waterborne diseases, their symptoms and causes, and which purification method can best eliminate them.

The best way to be certain about potential contaminants in water is to use a water testing kit.


Viruses are infectious agents that are very diverse in shape, structure, and behavior and can only replicate themselves when inside the cell of an organism. Once a cell’s nucleus becomes infected with a virus, that infected cell reproduces identical copies of itself at an alarming rate, ultimately taking over the entire system. Viruses can infect humans, animals, plants, and even bacteria.

A healthy human body will produce an immune response to a viral infection, ultimately eliminating the virus. These immune responses can also be produced by vaccines, which build immunity to specific viruses. While anti-viral medications can treat viral infections, antibiotics have no effect on viruses.

waterborne diseases

Pathogen: Norovirus

Disease: Gastroenteritis (Traveler’s Disease)

More commonly known as Traveler’s Disease, Gastroenteritis infects 20% to 50% of international travelers annually.

Norovirus, the virus responsible for the estimated 10 million cases of diarrhea yearly, is a highly contagious disease that attacks the digestive system and is typically transmitted through infected food and water or contact with infected surfaces.

Once inside the body, the virus disrupts the digestive tract, causing loose stool and abdominal cramps. The intestines and stomach become inflamed, causing severe stomach pain, nausea, diarrhea, vomiting, and fever.

Symptoms usually develop 12 to 48 hours after infection and cease after 1 to 3 days with a competent immune system. The virus is more likely to cause dehydration in older adults, younger children, or those with other illnesses due to excessive vomiting and diarrhea (CDC, 2018).


Pathogen: HAV (Hepatitis A Virus)

Disease: Hepatitis A

Hepatitis A is a communicable liver disease usually transmitted through fecal matter in contaminated food and water. Those who travel to places where Hepatitis A is common and not adequately treated are at much higher risk of infection.

Symptoms can be mild, lasting several weeks, or severe enough to last months. They usually occur within 2 to 6 weeks of infection and can include tiredness, muscle soreness, loss of appetite, fever, stomach ache, light-colored stool, dark yellow urine, and yellowish skin. In rare cases, Hepatitis A can cause liver failure and death but is more common in the elderly or those with compromised immune systems (CDC, 2017).

The antibodies produced as a result of the infection last for a lifetime and help protect the body against reinfection of the virus.


Protozoa are single-celled eukaryotes that feed on organic matter and can either be free-living or parasitic. They are similar to algae but too small to be seen without a microscope. Parasites are a type of protozoa which thrive at the expense of a host and usually dwell in the intenstinal tract. They can often live within a host undetected for long periods of time due to their resilient nature.


Pathogen: Cryptosporidium

Disease: Cryptosporidiosis

Cryptosporidiosis is a diarrheal disease caused by a microscopic parasite called Cryptosporidium. This parasite is protected by an outer shell, which allows it to survive outside of a host for long periods, making it resistant to chlorine treatment.  “Crypto,” as both parasite and disease are commonly known, lives in the intestines of infected humans and animals and is carried through the stool. Crypto is typically transmitted through coming into contact with water that has been contaminated with fecal matter containing the parasite.

Crypto is recognized as one of the most common water-borne diseases in the United States, with an estimated 748,000 cases occurring annually. Though usually found in recreational and drinking water, the virus also transmits through dirty swimming water, uncooked contaminated food, and close contact with infected people or animals.

The most common symptoms of infection are stomach cramps, watery diarrhea, vomiting, fever, and weight loss. Symptoms usually begin seven days after infection and can last up to 2 weeks. Those with weakened immune systems are likely to develop more severe and even life-threatening illnesses (CDC, 2017).


Pathogen: Giardia

Disease: Giardiasis

Giardia is a highly communicable microscopic parasite usually found in soil and contaminated human feces. Though its main mode of transmission is through contaminated water, it is also typically found on food and unsanitary surfaces. Like Crypto, Giardia also has a protective shell, allowing it to survive harsher conditions and making it more tolerant to certain disinfection methods such as chlorination. In order to kill Giardia through chlorination, allow the water to sit for 45 minutes, rather than the standard 30 minutes. For iodine, it's 50 minutes.

Giardiasis, the disease which Giardia causes, is a global disease. It infects 2% of adults and 6 to 8% of children in developed countries worldwide and hospitalizes about 5,000 people in the United States every year.

Children in childcare settings, outdoorsmen who drink unsafe water, and international travelers are at higher risk for Giardia infection. Symptoms usually start 1 to 3 weeks after infection and can include fatigue, vomiting, nausea, loss of appetite, greasy stools, diarrhea, bloating, excessive gas, abdominal pain, and headaches (CDC, 2015).


A bacterium, singular for bacteria, is a single-celled organism that lives as part of a colony whose numbers can reach into the billions. They are found in almost every environment on earth and can withstand a wide range of conditions and temperatures. Bacteria aren't necessarily harmful to the human system. In fact, tens of trillions of microorganisms which include over 1000 different species of bacteria are responsible for the proper and healthy functioning of our digestive tract (Gut Microbiota).

Bacteria are extremely adaptable and can build resistance to antibiotics over time. Due to the increased amount of processed foods that humans have consumed through recent years, digestive tract bacteria have adapted to use both organic and inorganic material as a food source.


Pathogen: Campylobacter Jejuni

Disease: Campylobacteriosis

Though most commonly transmitted through eating raw or uncooked poultry, Campylobacter can also be transmitted through contaminated water, contaminated food, animal contact, and unpasteurized milk.

With a strong enough immune system, it is possible not to show symptoms after becoming infected. However, for those with weakened immune systems, such as people with AIDS, blood disorders, or those receiving chemotherapy, Campylobacter can spread into the bloodstream, causing a life-threatening infection.

Symptoms of the disease are diarrhea, fever, stomach cramps, and vomiting, typically starting within 2 to 5 days after the infection.

About 1 in 1000 people infected with Campylobacter can develop GBS, a more serious disease affecting the immune system.

Most people recover from the disease within a week, although the bacteria may remain in the stool for several weeks, posing a risk for further person-to-person transmission.

Though not often fatal, this bacterium is one of the four most common causes of diarrhea worldwide. Every year, it affects around 1.3 million people in the US and 550 million people globally. For reasons unknown, Campylobacter infection has been increasing in developed countries for the past several years (CDC, 2017).


Pathogen: Legionella

Disease: Legionnaires' Disease

Legionnaires' disease is a type of pneumonia caused by Legionella, a bacterium found in freshwater environments such as lakes and streams. It becomes a health concern when bacteria enter human-made water systems such as water tanks, hot tubs, plumbing systems, and showerheads and faucets. It thrives in water temperatures between 95 to 115 degrees Fahrenheit.

Unlike most water-borne diseases, Legionnaires’ disease isn’t transmitted by direct human contact but through tiny water droplets in the air or mist. A person becomes infected when the water droplets are breathed in and enter the lungs. 

Legionella derived its name from its first outbreak in 1976 when 129 out of 2000 people who attended an American Legion convention became infected. Among those infected, 29 died. In the US, there are between 8,000 and 18,000 reported cases of Legionnaire’s disease every year. About 10% of those who contract the disease die.

Many people exposed to the bacteria may not even develop the disease. However, there are risk factors that increase the likelihood of infection, such as old age, chronic lung disease, smoking, and a poor immune system. Symptoms of the disease include cough, fever, muscle pains, shortness of breath, vomiting, and occasionally, diarrhea.

There is no known vaccine to immunize from the disease. One way to prevent exposure is to take clean water precautions, especially with drinking water. If infected, antibiotics and hospitalization will be required (CDC, 2018).


Pathogen: Shigella

Disease: Shigellosis (Dysentery)

Shigellosis is a highly contagious waterborne disease caused by Shigella, a bacteria that thrives in fecal matter. Transmission can occur through drinking contaminated water or when someone puts infected material in his/her mouth. Frequent handwashing is an effective way of limiting Shigella transmission.

Symptoms begin 1 or 2 days after exposure to the bacteria and resolve within 5 to 7 days with a healthy immune system. Some might not show any symptoms at all but can still transmit it to others.

Infected people will show symptoms of fever, stomach pains, and diarrhea. Young children, travelers, and those with weakened immune systems are more likely to contract the disease.

The Shigella bacteria can cause severe complications like dehydration, rectal bleeding, and seizures in small children. The most severe of complications is death by contamination of the bloodstream. Of the 700,000 deaths each year, most of these fatalities happen in developing countries where there are very few water treatment programs and where sanitation is a constant challenge.

An estimated 18,000 cases of Shigellosis occur in the United States every year (CDC, 2018).

salmonella 2

Pathogen: Salmonella

Disease: Salmonellosis

Discovered by American scientist, Dr. Salmon, salmonella is a bacterium that thrives in fecal matter and is transmitted through raw meat, raw eggs, fruits and vegetables, and contaminated water. Those at higher risk for infection are those who travel internationally, those who own birds or reptiles, and those with bowel disorders and weakened immune systems.

Drinking water becomes contaminated when wild animals defecate into streams and rivers.

People who develop salmonellosis will show signs of diarrhea, chills, abdominal cramps, and fever. The fever can last up to seven days and with adequate hydration, most people can recover without medical intervention.

Every year, out of the 1.2 million people who get infected, 23,000 need hospitalization (CDC, 2018).

salmonella typhi

Pathogen: Salmonella Typhi

Disease: Typhoid Fever

Salmonella Typhi is the bacteria that causes typhoid fever. Globally, it causes roughly 17 million infections and 200,000 deaths every year. A subspecies of the Salmonella bacterium, salmonella typhi, can only affect humans and is more common in developing countries where hygiene is poor.

About 400 reported cases of Typhoid Fever in the United States every year, 75% of which are due to international travel.

Salmonella typhi grows in the intestines and blood and is transmitted through water or food contaminated with the feces of an infected person. A typical contamination process is when stool, buried in the soil, comes into contact with a close water source, usually a deep well. The water supply, when contaminated, can also contaminate the food. The bacteria can survive for many weeks in water or dried sewage.

Symptoms can appear anywhere from 6 to 30 days after exposure and can include fever as high as 104 degrees Fahrenheit, abdominal pain, lethargy, diarrhea, severe headaches, and poor appetite. If not treated immediately, typhoid fever can be fatal in up to 20% of infected people. Prior vaccination is highly recommended when traveling to countries where typhoid is rampant (CDC, 2018).


Pathogen: Vibrio Cholerae

Disease: Cholera

Vibrio cholerae is the bacteria responsible for cholera outbreaks. Cholera was a highly infectious disease prevalent in the 1800s when proper water treatment systems were not yet in place. Though rare in the United States today, cholera is still pervasive in developing countries with poor sewage systems.

Every year, around 150,000 cases of the disease are reported by the World Health Organization. With a 1% mortality rate, cholera treatment has gained significant headway in recent years. However, if left untreated, the chances of dying increase to 60%.

Once infected, the common symptoms are diarrhea, dehydration, muscle cramps, rapid heart rate, low blood pressure, loss of skin elasticity, and excessive thirst. Without proper treatment, death can occur within just a few hours (CDC, 2018).

E coli

Pathogen: Escherichia Coli

Disease: Verotoxic E. Coli

Escherichia Coli, more commonly known as E. Coli, is a type of bacteria that lives in the intestines of humans and animals. Though most strains of E. coli are harmless, some can cause serious damage in the form of Verotoxic E. Coli, which infects around 100,000 people and kills 90 every year in the US.

Once infected, symptoms usually start within 3-4 days of exposure, including abdominal pain, diarrhea, vomiting, and fever. Those with healthy immune systems usually heal within 5 to 7 days. If left untreated, those with compromised immune systems can escalate into dehydration, intestinal infection, kidney failure, and death.

The disease is usually transmitted through unsafe handling of food and contaminated water. Poor sanitation can move bacteria from humans or animals into the water stream (CDC, 2018).


Waterborne pathogens are everywhere, but it is up to us to ensure we take the proper precautions to reduce the risk of exposure. Even though those in developed parts of the world have the privilege of modern infrastructure and sanitation systems, there can never be a 100% guarantee that all the water we come into contact with will be pathogen-free. One crack in a water pipe can put the entire water supply at risk of exposure.

Proper knowledge of the potential risks is essential when traveling, camping, or preparing for water storage at home. When overseas, only drink water from trusted, properly sealed bottled sources. When unsure of the quality of a water source, always err on the side of caution and avoid it or apply the proper purification methods. Be aware and informed, and keep yourselves and your family safe.

Thank you for taking the time to read our article on common waterborne diseases. We'd love to hear your feedback in the comments section below. If you've found this article to be useful and are interested in learning more, be sure to sign up for our newsletter.

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CDC. (2015, July 22). Giardia. Retrieved from https://www.cdc.gov/parasites/giardia/index.html

CDC. (2017, September 29). Hepatitis A Information. Retrieved from https://www.cdc.gov/hepatitis/hav/index.htm

CDC. (2017, January 12). Parasites - Cryptosporidium (also known as "Crypto"). Retrieved from https://www.cdc.gov/parasites/crypto/index.html

CDC. (2017, October 25). Campylobacter (Campylobacteriosis). Retrieved from https://www.cdc.gov/campylobacter/index.html

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CDC. (2018, April 30). Legionnaires Disease and Pontiac Fever. Retrieved from https://www.cdc.gov/legionella/index.html

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CDC. (2018, June 28). Typhoid Fever. Retrieved from https://www.cdc.gov/typhoid-fever/index.html

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CDC. (2018, April 20). E.coli (Escherichia coli). Retrieved from https://www.cdc.gov/ecoli/index.html

Gut MicroBiota. (n.d.). Gut Microbiota Info - Gut Microbiota for Health. Retrieved from http://www.gutmicrobiotaforhealth.com/en/about-gut-microbiota-info/

I'm Jeremiah, the owner of World Water Reserve. I'm a writer and researcher with a particular interest in sustainability and rural living, water scarcity, and innovative water purification methods. I utilize my multimedia and communication experience in the NGO and humanitarian fields to bring light to important topics. My passion is to educate others on the reality of the global water crisis and on ways to sustain themselves and their families in the midst of it.
Jeremiah Zac